Cruz,
Without the spark arrestor it will be loud as HELL !

 

COOL Loud is good

 

The R-4 Puts out 3-4 hp on a Raptor. I had two of them before and yes its louder with out the screen. But, if your looking for a new R-4 Good luck. They discontinued that bad boy. Maybe because of the decible laws I would guess.

 

I have the E-Series though.. Is that any good or...?

 

I had that one first but didnt care for it. I switched to the R-4 and it really felt much better and the sound was awesome.

 

Was the power any better or different?

 

I personally noticed it. Thats why I put one on each bike after that. Now I have the Sparks pipes which are way better but more $$$.

 

You'll probably have to change pipes if you want to beat your friend on the top end.

The E series actully subtracts peak HP from the Raptor, but it adds an impressive 7 hp at low to mid RPMs. I am not sure you can modify it for top end performance without loosing those huge gains in the low end. I ran mine for a couple months and then dumped it on EBAY for this reason.