Realistic gains to expect from an intake?

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Originally Posted by blueguy

Hell froze over...

Because this is correct.

If your stock L67 car makes 200WHP or more, you'll be lucky.

Adding headers lowers boost numbers because the car is flowing more freely...you then add the pulley to make up for the loss, because all it is doing is shifting the power up...you're not losing ANY power, and it's easier to launch because the torque is now geared a little higher in the band.

HiPo Pontiac did a test I think on an SSEi back in the day, and it gained close to 30WTQ and north of 20WHP. L36 gains were close as well...because I think they tested a GP GT too, just to compare...and to show how crappy and restrictive the manifolds to the catback really are.

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So am i actually making more power with headers on a stock gtp, and moving the power band, or is the powerband just moving without creating power?

Im talking staying on a stock pully,
i know if i drop a pulley size to like a 3.5 with headers it adds power.

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Originally Posted by GTP131

I've "felt like" I lost some low end when I added headers with stock pulley, but gained a good chunk of top end. No dyno numbers to verify this, though.

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You didn't lose any low end. You just gained more in the top end than you gained in the low end.
Headers don't lose power at any RPM.

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Originally Posted by Scottydoggs

you loose boost for sure, it did gain power off the line i said, ( headers will let it melt the tires) but its no faster then stock to me. till you add a smaller pulley. butt dyno

and the intake dont add those numbers, you know that.


and thats crank HP as the dealer would post it. not to the wheels.

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Pay attention you guys are saying exact opposite things here.
Headers gain 15ish peak whp... but at very high RPM the gains are even bigger.
At 6000+rpm I've seen a 30whp gain over stock without a tune or pulley.

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Originally Posted by SnowFlake

You didn't lose any low end. You just gained more in the top end than you gained in the low end.
Headers don't lose power at any RPM.



Pay attention you guys are saying exact opposite things here.
Headers gain 15ish peak whp... but at very high RPM the gains are even bigger.
At 6000+rpm I've seen a 30whp gain over stock without a tune or pulley.

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Hopefully this is for n/a too cause I always wondered if I should of sold my headers with the top swap instead of installing them

Headers will be a gain whether N/A or SC at any RPM because its flowing better. I didn't swap pulley on my car and butt dyno was greatly improved.

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Originally Posted by SnowTh1ef

Headers will be a gain whether N/A or SC at any RPM because its flowing better. I didn't swap pulley on my car and butt dyno was greatly improved.

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Thanks man, that cleared it up. i would think that since the same amount of air is going into the engine, the boost pressure reading would be less determinant of the power the engine is making.

Less boost isn't necesarily less power, if the engine is flowing better and theres less KR.