Quote:
Originally Posted by brucelidat
Everyone I talk to says it doesn't make sense for the SC to make less power with headers/test pipes unless the SC unit can't push enough air which they say shouldn't be the case with the vortech unit in the kit. It has been suggested to me that Stillen's stance might be based off of their CARB approval and not being able to endorse race applications because of it.
Are there any independent customer dynos to confirm this claim of lower power with headers/TPs?
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There are several customers who have proven this. I don't think I have the dyno sheets, but several reputable forum members have proven you lose 10-20 whp when going away from stock cats.
It has nothing to do with the flow. You have to understand the valve timing of the VQ37 and how VVEL works. We only have so much control of the valve timing and overlap. There is still some valve overlap that lets some of the boost escape into the exhaust during the intake cycle. The backpressure from the Cats actually helps keep some of the boost in the cylinder which makes more power (though headers and test pipes are more efficient at moving the exhaust gases, the loss in boost pressure in the cylinders results in less power).