General consensus on boltons to gain the most HP.

Jordo!

No. Everyone's car will respond similarly because everyone has the same motor.

The problem is you have to make comparisons using the same type of dyno (or dyno settings if not a dynojet), same correction factor, and have a clear baseline for comparison. Across dynos, the percentage gain should be similar for a given mod.

The data from dynojets is pretty clear and the gains I've seen from various mods on different members' cars are predictiable.

The major variable seems to be that the first breather mod often seems to gain more power than when the same mod is the second or third bolt on (e.g., intakes seem to result in larger net gains when done first, but not second or third).

I'm not exactly sure why that is, but for simplicity, let's just assume it's due in part to limited room for improvement and dimnishing returns as you get closer to optimized VE for the motor (VVEL tuning might open up more possiblities there...)

The only possible exception might be removal of the factory cats, which does seem to be a consistent bottle neck that always nets decent gains; although again, probably higher if done first.

Put your car on a dynojet, use SAE correction, and I can pretty much guarantee you that if your motor is sound, bone stock you will put down about 273 whp +/-5 (I'd say 288 - 290 +/-5 for a Nismo).

I can give you guys more accurate estimates as I get more data -- please send me those drf's if you got 'em

Who is making 330-340 whp N/A? Not on a dynojet. Link?

Actually I've hardly seen anyone break 300 on a dynojet (especially SAE corrected -- STD tends to overcorrect towards higher values) who isn't in a modded Nismo. I think you may be mistaken...

And yet, I've seen no independnet dynos that report equivalent gains... Sorry, but I'm not buying it. Also, see my comment about the first breather mod's effect.

EDIT: Also, STD correction almost always skews high (appropriate for FI, but tends to overestiamte for NA).

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