how much hp would an rrm intake and a test pipe yeild. also, has anyone ever ran the test pipe with the stock muffler? how does it sound? thanks guys

 

Maybe 3 or 4 at the peak.

I don't suspect the test pipe would change the sound much, but I'd probably spit out some nasty smelling exhaust.

 

Testpipe w/ stock muffler equals almost no noticeable sound difference and even less noticeable power difference. You'll definitely feel the car pulling more in the lower rpms cuz of getting rid of the stock airbox, but with the stock exhaust piping, the top end is still gonna feel lacking. 3 or 4 hp tops sounds good.

 

I noticed a difference when I put the RRM testpipe on with my GReddy exhaust.

Before:
AEM Intake, Stock Cat and GReddy Exhaust.....Idle sounded deep and 4000-5000 rpm sounded like a deep evil growl.

97 DB was the loudest reading.

After:
With the Testpipe.....Idle sounded deep still and 4000-5000 rpm sounded like the same deep evil growl but MUCH louder. Towards 6000 rpm the sound went from a growl to a howl and was borderline deafening.

105 DB was the loudest reading.