If you are leaving the catalytic converter alone, probably not since the crossover pipe is still in play. Swapping out only the silencers might lead to some lean conditions during deceleration and you get the 'pop' in the exhaust. The way to see if it's running lean under load is to accelerate hard, pull in the clutch and hit the kill switch. Coast brake to a stop, pull a plug and check the color. Chocolate brown and you're good, white too lean, black too rich. Kind of a PIA but it will give you a sense of how the fueling is working under load without putting it on a dyno. If you don't mind spending the money, get it dyno tuned and it will have max power throughout the rev range.
