Thread: Stock cat-back good to 300whp??

Interesting


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Before with the ported Gen 3 and 2.5" SLP exhaust (Single pipe)



After with the 3" exhaust and same Gen 3.



well looks more like 17-20 WHP. I have a graph somewhere of 258 (difference was I upgraded to 105 valve springs).

When I changed the valve springs (3" exhaust, gen 3)...