Ye thats right and thats the size of an rc40, as with sound i believe they are quite nice, but you will get a better sound from a wider exhaust in my opinion. But do you want a to sacrifice power for sound. A question you should pissibly ask is what sort of power difference will it make?
So does increased bore reduce power?
The exhaust internal bore diameter is important. Too small and it restricts the flow of the exhaust gas and too large and the flow speed along the pipe is too low and power is lost. That's a simplification of the physics, but the key thing is that at the revs where the cam/head combination are able to give best power, the speed of the exhaust gas molecules must be correct from the end of the exhaust manifold to the final output from the exhaust pipe. It has been found that for 1275 engines the optimum is 1.75" internal diameter and for the 998 it is 1.625" I.D. If a larger final output pipe is fitted (or even those useless twin pipes), the exhaust gas pressure in that larger pipe will increase and the gas velocity will reduce and that is also bad for power. At revs over about 7500 rpm with a 1275 a 2" int. dia. pipe is fine, but that is for out & out race engines really.
