I've just installed the new style Kooks headers with kooks high flow catted x-pipe, slp loud mouth catback exhaust and my car now feels like 30-40hp slower at mid to top rpms. Lower RPM's do feel quicker. I have Billet Flow 2.76" pulley and that thing used to whine loud and now you cant here it all with new exhaust setup. The old exhaust setup was stock manifolds, O/R X-pipe and Flowmaster Catback exhaust. I did notice a drop in boost guage around 2-2.5lbs of boost after install. I have been told that boost drop off is normal with header install due to less back pressure but is 2-2.5lbs of boost drop of normal. Would switching back to flowmaster catback give it more back pressure and add a little boost over slp loudmouth catback exhuast.
Kooks Headers 1 5/8" with 2.5" collector
Kooks Catted X-Pipe 2.5" Collector 2.5" Out
SLP Loudmouth I Catback Exhaust
Kooks Headers 1 5/8" with 2.5" collector
Kooks Catted X-Pipe 2.5" Collector 2.5" Out
SLP Loudmouth I Catback Exhaust
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