id guess that the stock manifold (1 of them) weighs about 6 or 7lbs. and a hedder weighs about 3-4 depending on what one. id say 4 for the hooker super comp. im just guessing but i assume a hedder weighs about 40-50% lighter.
I think it'll be close to a wash. 30" tubes x 4 (1-5/8" OD x 16 ga) is a little over 10 lbs just in the header individual tubes. Add a lb or so for the collector and its flange and a couple of lbs for the head face flange and each header side is 13 - 14 lbs. I'm thinking the iron manifolds are closer to 8 lbs apiece, and then you have to add 2 - 3 lbs for its head pipe to match up to the same place that the header would connect to. 13.5 (header) vs maybe 10 - 11 (manifold) per side? 5 lbs total?
Norm
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08 GT Premium Black/Light Graphite, stick, un-FStock weenie-EP 626/V6, Prepared just enough, sometimes
Manifolds are cast iron and restricts exhaust flow.Headers flow a lot better and most are equal length tubes so they flow great.Only downside to headers is long tube ones can drag on speed bumps if your cars lowered.
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Weight difference between manifold and headers? - 
