Quote:
Originally Posted by semtex
All in all, I have mixed feelings on this (based on the DD results). I like the HP gain. I like 317.2 a lot better than 306.4. But I'm not pleased about the loss of lower mid-range torque.
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Are you sure that the low-rpm torque loss wasn't just from ramping the throttle in? On my DD run, I don't really trust any of the numbers under 3750 rpm or so as I'm pretty sure the engine wasn't solidly WOT until shortly before 4K. Even then, the way my torque doesn't really peak up until about 4250 is suspicious (this may have been lag between hitting WOT on the pedal and the engine really starting to breathe like WOT).
Given the data we have so far (including yours), I think it's fair to say that the headers aren't great bang per buck (and especially aren't good bang per installation hour), but I have a hard time believing we really lost torque on them given the graphs and the unknowns.
There's also the ECU consideration. The headers may provide better gains under good tuning (or not), we'll have to see.