One for RGHO I suspect. I have a 1700cc twincam with a large bore exhaust from downpipe to the silencer, but the outlet pipe from the silencer is standard size. Would it benefit breathing to wop on a larger final pipe - perhaps the same size as the inlet pipe to the silencer? D
I dont think it will help greatly but it certainly will not hurt
cheers
Rohan
Just up your strasse, David:
amazon.co.uk/AB-Tools-Screa … r=8-3&th=1
‘… a deep, powerful raspy sound …’
Will make you feel 16 again…
John 
Well yes - or no probably! I like a quiet exhaust with just enough “on song” sound as the revs rise. I asked the question because the original tail pipe on my “S” type silencer is really quite small and I just thought with 1700cc, big valves, QED 420s and quicker exit may just liberate a bit more thrust. Less back pressure and all that malarky. Rohan thinks It will not make much difference and he should know. D.
When constructing the exhaust for my Zetec Plus2, I found that the inlet pipe to the muffler, and the short outlet pipe were smaller in diameter than the piping within the muffler. As my exhaust is an expanding one, the piping increases in diameter in specific lengths from the cylinder head to the muffler. The arriving pipe diameter to the muffler was the same diameter as the internal piping within the muffler, so both inlet and outlet piping was cut off and equal diameter piping within the muffler was welded on. Not sure if it made any difference in performance, but it made me feel better. The sound is not the least bit offensive to me, and there is no droaning at cruising speeds.