Vintage Speed 43mm on a 1915?

Hello,
Thinking of a 38mm Super Sport (quiet ) or a 42mm full system for my 1915, but think the 42mm may be may be to big and noisy, currently have a Fatboy it's noisy.
Anyone running 38 or 42 on theirs and what are the downfalls if any?
Any information would be a great help.
Thanks
Darryl

I ran 38 mm pipes more than big enough for 1916 engine

Also made the front pipes fit inside heater boxes to keep warm in winter

pm sent

Are you running heater boxes?

No point running a 42mm system if you are.

What sort of HP are you getting.

I ran 38mm (stock) on my 1916 with heater boxes and that made ~75 HP at the wheels.

Unless you are going for 100+ ponies I would stay with the38 mm system

Bizarre wrote:Are you running heater boxes?

No point running a 42mm system if you are.

What sort of HP are you getting.

I ran 38mm (stock) on my 1916 with heater boxes and that made ~75 HP at the wheels.

Unless you are going for 100+ ponies I would stay with the38 mm system

HI,
Standard crank, twin 40 carbs, stock heads, 12 lb flywheel, 1.25/1 rockers, magna spark dist, and it goes quiet well.
I noticed more torque after fitting the rockers.

No Heater boxes, unknown horsepower, So I ordered a 38mm, should be a lot quieter, I'm half deaf and it's still to noisy.

Thanks for the input.