Posts: 2533
Joined: 12/2/2003 From: Sacramento, CA Status: offline
When it comes to aftermarket headers get what fits your car, no need to do all the custom modding for those. If you dont have the cast for aftermarket shorties for your car and you have a 99+ then this mod is ideal for you.
If you live in a state where there is no smog regulation then I say go for the long tubes, they are one of the better mods for your car. The LT's with midpipe and GT takeoffs will put a kick in your pants :)
If you already have other mods done like CAI, TB, any kind of portwork and higher ratio roller rockers the kick will be magnafied.
Posts: 2533
Joined: 12/2/2003 From: Sacramento, CA Status: offline
Just get the ones that fit your application year, in that case it doesnt matter too much, you are going to need to get a Midpipe anyways. I am pretty sure that MAC makes their LT collector size 2.5" so I think your safe there :)
This header guild mainly applies to those who have a 99-04 model and are looking for extra performance cheaper than they can with aftermarket headers. It also shows the 94-98 guys that their headers are great as they are and really dont need to purchase a $400 dollar set of shorties :)
Thank you very much for the information, I appreciate this. I am here in LA and for me to get a set of 94-98 set of headers and to get them coated cost almost as much as the aftermarket headers. I am still looking though. Furthermore I am trying to get the most bang out of a buck. Thank you again.
Posts: 2533
Joined: 12/2/2003 From: Sacramento, CA Status: offline
If you dont have smog in your state get the Mac long tubes and the Mac midpipe. Get the one that fits yours year.
If you are a 99-04 Model and want shorty headers then get 94-97 headers and save a ton of money. You will need to do a little modification like extending the EGR tube and having a shop expand the collector flanges on the Y-Pipe.
ok so i have learned that the collectors on my 98 are 2.25". does that mean that the first set of cats are 2.25" in/out or not? and are the first set of cats consiterd "pre cats" or are they? also if i got the magnaflow cats would i need all four to be legal. all four meaning the first set of cats then the magnaflow cats or could i just use one magnaflow cat on each tube and be legal?
Posts: 2533
Joined: 12/2/2003 From: Sacramento, CA Status: offline
I am not sure about the size of the ID / OD of the cats, mine were stolen while I ate dinner one night by the kid down the street (Cops didnt do anything, after they left I watched them take it away in their van.) I do believe that they are though.
You will need all four cats in the same spot and same length on the Y-Pipe to pass in California, I dont know if its that way for other states. Being that California is the benchmark for smog I would stick with that set of rules. I would however make a set of test tubes so that you can slip two or all out whenever you feel like it.
I had to modify that ceramic coated 1995 BBK O/R X-Pipe that I had to fit my headers after the Y-pipe was stolen. I had a local shop weld smaller flanges on to accept the female header flange. I brought a bare 3.8L block in with a set of heads bolted on it and the headers so they could fab it up perfectly. They also raised the front of the block 3 degree's to simulate how it would sit in the car. Everything was perfect and it even lined up to the trans mount perfectly.
Starting the car the first time with the new engine, ported heads, intake, plenum and headers was crazy! It sounded like I had a 5.8L with a mean MEAN cam in it. I even got the cops called to my house where they cruised by repeatedly. I took it around the block just once and off idle it felt like that 03' GT 5spd that I had test driven. So the torque and low horsepower was there but I never got out of 3rd or higher than 30mph. I am having some fuel problems right now with my CPS and I will be changing that this week.
At higher rpm's it begins to sound high pitched but thats fine :) I just need gears now.
2004 V6 3.9L: I dont know the exact gains for LT's and dual exhaust, its greater over shorties for sure but not smog legal in California even with cats. In California you need to keep your cats in the same place as factory, doesnt matter if you put 20 cats on your car, if you moved them it wont pass inspection.
Now chances are that no one will ever look under your car (Except a Cop) for cats that arent in the right place so thats why I suggest two sets of exhaust if you can afford it. One that is emisions compliant and one that is built to how you like it with test tubes. That way if you get a Fix-It-Ticket then you just pay the $25 dollar court fee and the $20 dollar inspection fee and put your stock exhaust back on. After you pass then do what you want again.
What we are going to do with the BBK X-pipe is get two high flow cats and clamp them in the stock lower location and leave the uppers out. We will still pass smog (Maybe anyways) and we will only have to get two cats. If we ever go through inspection or a cop should become wise to us then we will have to get the other two clamped in too. Though that is the beauty of the test tube.
We just have to find some GT takeoffs now :)
Sorry I couldnt give you more help on how much power it nets ya. As for the smog laws, I would just try to keep is stock and build a special exhaust on the side for yourself, that way you can always go back to stock if cought :)
sorry neotokyo but i have to ask you this question(sorry because you are gettin bombarded...) i was thinking bout getting headers for my 01 with a new exhaust too. if i put 94-98 stock shorties what size does the x-pipe/midpipe have to be. i might not be completely accurate with this question so sorry if i'm wrong with the wording of the question
excellent post, very informative, i got a few question,
i just order some 95 exhaust manifolds for my 2000,
the stock manifold has an egr tube in the front of the drivers side on, the 94-98 does not, so i was planing anyway on deleting the EGR, can any exhaust shop cover the egr holes?
my exhaust is basically the stock one until the catback, can i enlarge the flange and use it with my 00 exhaust manifolds so when i change them they bolt right up? or can i bolt the 2 flange at the 2 1/4 from the manifold and later opened them a bit.
what mid pipe can i get for this manifolds? any 96-98 mustang gt x/h would work, ? or does it gotta be one specifically for a 94-98 v6?
and the o2 sensors, can i tell the shop to cover the o2 holes on the 94-98 manifolds and leave them in the other tube? or the gotta be in the manifolds?
sorry for my question but i dont wanna run on any trouble when i install thanks!
excellent post, very informative, i got a few question,
i just order some 95 exhaust manifolds for my 2000,
the stock manifold has an egr tube in the front of the drivers side on, the 94-98 does not, so i was planing anyway on deleting the EGR, can any exhaust shop cover the egr holes?
my exhaust is basically the stock one until the catback, can i enlarge the flange and use it with my 00 exhaust manifolds so when i change them they bolt right up? or can i bolt the 2 flange at the 2 1/4 from the manifold and later opened them a bit.
what mid pipe can i get for this manifolds? any 96-98 mustang gt x/h would work, ? or does it gotta be one specifically for a 94-98 v6?
and the o2 sensors, can i tell the shop to cover the o2 holes on the 94-98 manifolds and leave them in the other tube? or the gotta be in the manifolds?
sorry for my question but i dont wanna run on any trouble when i install thanks!
why delete the EGR? if an inspection station notices it's deleted they will fail the car.
an easy fix is to run high temp silicon emissions hose from the 95 EGR port to your EGR valve and you will need 2 small emissions hoses to go from the header to the purge valve. the easiest way to do it is to get an EGR tube from a 94-98 and cut it just above where the small nipples come off of it for the purge valve hoses. it will work with about $50 invested and be 100% emissions legal.
NEO must not have heard of early 94's coming with cast iron headers. some came with them and they have roughly the same dimensions as 94-98 tubular stock headers but they could be extrude honed smooth and opened up alittle for better flow. they are very rare. i have only seen 2 cars with them. the Haynes mustang manual has a pic of a 3.8 stang engine with them too
_____________________________
98 3.8L 11psi Procharger 1.8's,3.73`s,7.5 Detroit Truetrac,TA rear girdle,B&M shift kit,2500 stall,8.5:1 ross .030" pistons,Eagle H-Beam 351W rods,RPM 215/230 cam,SCT chip from VMP,Pro-M Univer MAF,ford 42lb injectors
If you dont have smog in your state get the Mac long tubes and the Mac midpipe. Get the one that fits yours year.
If you are a 99-04 Model and want shorty headers then get 94-97 headers and save a ton of money. You will need to do a little modification like extending the EGR tube and having a shop expand the collector flanges on the Y-Pipe.
Neo you have great technical advice on these headers for these years, but the bolded statement will mislead people. The requirement for catalytic converters is a federal law enforceable in all states. Any automotive mechanic doing vehicle inspections "could" fail your car without them. In some locations where states are required to do more pollution control (ozone nonattainment areas), more intense emissions control equipment inspections are required. A missing cat will immediately show-up under that kind of inspection, and you will be failed. Someone deleting cats and or putting in an O/R setup in a county of a state where these emissions inspections are not required is simply getting away with violating the law.
excellent post, very informative, i got a few question,
i just order some 95 exhaust manifolds for my 2000,
the stock manifold has an egr tube in the front of the drivers side on, the 94-98 does not, so i was planing anyway on deleting the EGR, can any exhaust shop cover the egr holes?
my exhaust is basically the stock one until the catback, can i enlarge the flange and use it with my 00 exhaust manifolds so when i change them they bolt right up? or can i bolt the 2 flange at the 2 1/4 from the manifold and later opened them a bit.
what mid pipe can i get for this manifolds? any 96-98 mustang gt x/h would work, ? or does it gotta be one specifically for a 94-98 v6?
and the o2 sensors, can i tell the shop to cover the o2 holes on the 94-98 manifolds and leave them in the other tube? or the gotta be in the manifolds?
sorry for my question but i dont wanna run on any trouble when i install thanks!
why delete the EGR? if an inspection station notices it's deleted they will fail the car.
an easy fix is to run high temp silicon emissions hose from the 95 EGR port to your EGR valve and you will need 2 small emissions hoses to go from the header to the purge valve. the easiest way to do it is to get an EGR tube from a 94-98 and cut it just above where the small nipples come off of it for the purge valve hoses. it will work with about $50 invested and be 100% emissions legal.
well, were i live they dont check for that, they only make sure you have your cats and thats it, so deleting the egr is no problem for me, i thought of it because is a lot easy than do all the process you said.
but what about the other stuff, what do you think?
excellent post, very informative, i got a few question,
i just order some 95 exhaust manifolds for my 2000,
the stock manifold has an egr tube in the front of the drivers side on, the 94-98 does not, so i was planing anyway on deleting the EGR, can any exhaust shop cover the egr holes?
my exhaust is basically the stock one until the catback, can i enlarge the flange and use it with my 00 exhaust manifolds so when i change them they bolt right up? or can i bolt the 2 flange at the 2 1/4 from the manifold and later opened them a bit.
what mid pipe can i get for this manifolds? any 96-98 mustang gt x/h would work, ? or does it gotta be one specifically for a 94-98 v6?
and the o2 sensors, can i tell the shop to cover the o2 holes on the 94-98 manifolds and leave them in the other tube? or the gotta be in the manifolds?
sorry for my question but i dont wanna run on any trouble when i install thanks!
why delete the EGR? if an inspection station notices it's deleted they will fail the car.
an easy fix is to run high temp silicon emissions hose from the 95 EGR port to your EGR valve and you will need 2 small emissions hoses to go from the header to the purge valve. the easiest way to do it is to get an EGR tube from a 94-98 and cut it just above where the small nipples come off of it for the purge valve hoses. it will work with about $50 invested and be 100% emissions legal.
well, were i live they dont check for that, they only make sure you have your cats and thats it, so deleting the egr is no problem for me, i thought of it because is a lot easy than do all the process you said.
but what about the other stuff, what do you think?
if they check for the cats then your area requires the EGR to be intact too. Federal Law requires it to be intact and it really doesn't hurt performance so why not just use it???
_____________________________
98 3.8L 11psi Procharger 1.8's,3.73`s,7.5 Detroit Truetrac,TA rear girdle,B&M shift kit,2500 stall,8.5:1 ross .030" pistons,Eagle H-Beam 351W rods,RPM 215/230 cam,SCT chip from VMP,Pro-M Univer MAF,ford 42lb injectors
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RE: Once and For All 94-98 VS 99-04 Header guide! STICK... - 
) and we will only have to get two cats. If we ever go through inspection or a cop should become wise to us then we will have to get the other two clamped in too. Though that is the beauty of the test tube. 
