AO Silver Member
Join Date: Jan 2003
Location: idle to 7500rpm
The larger the center pipe (given the rear muffler is relatively high flow), the better the power at the top end of RPM. Smaller pipe usually yields more power at lower end due to back pressure as Stori said. But damaging the valve is unheard of. So it all depends on your driving style and preference.
I had Novitec kit on, and the center pipe is big (65mm or 70mm, not sure), and from 4,000rpm to redline, there's good power delivery and throttle response, if a little too loud. My Supersprint kit has much smaller center pipe (~50mm?) and it's certainly not as responsive in the top end, but it sounds better.
//2000 156 2.0TS / AD Remap / Supersprint Exhaust / K&N Filter Kit / Rhoddy Harvey-Bailey Suspension / AR Strut bar /16" Telephone dials + Yokohama V550 / Tar-Ox discs + SS lines + MQ pads //
//2005 Subaru Impreza WRX PPP / K&N Short Ram-air Intake / Brembo 4-pot Brake Kits / Prodrive GC-010 British Black 18x7.5 Forged Alloys / Michelin Pilot Sport Cup / Prodrive Spring Kit / STi Aero kit //