WHICH EXHAUST ?

[holty]

my pal has a road tuned 175 gori with a 25delly and a 42mm clubman, he is thinking about a change of exhaust to gain a little more power, but he doesnt want to change his final drive ratio which is 5 to 1,which exhaust would you recomend for him,
thanks in advance,
holty

[soosh]

Does he have a bigger carb kicking around?
A 28mm even on that setup will make a difference.