i got a d15b non vtec, and my car was hella loud (just the engine) when i floored it, now im not sayin its fast by all means, but when i got a new dizzy installed, it seems to not be AS powerfull, and not as loud???? could it be the timing?

 

Air filter clogged?
Highflow (from stock) air filters would make the throttle sound louder.

Never heard of New Dizzy's changing sound ( OEM, not aftermarket)