The Spin Doctor wrote: ↑Thu Apr 08, 2021 9:35 amErrrr. No.Rockburner wrote: ↑Wed Mar 31, 2021 10:55 amBut isn't that what we all believe? Louder = more powerful. It's the lie that's sold virtually every exhaust modification since 1905.
My observation is that it's what owners want OTHER people to believe!
To be fair and if magazine tests are to be believed, right into the 80s a 'race exhaust' did liberate some extra power and was certainly a lot lighter. Some of the magazine tests showed 10% gains.
I had a Seeley exhaust (they weren't called cans back then) on my 400-4 and I was amazed at how light it was compared with the OE silencer. Whether the bike was any quicker, I don't know, but it made a nice sound - it was fruity rather than loud. And well-made two-stroke spannies certainly liberated quite a bit of power even if the three-into-one jobs on KHs and GT triples certainly didn't. The Allspeed on the Team Fiendish AR50 Endurance Racing Moped (plus some porting) really did work - we got that 50cc bike up to a top speed of over 60 mph!
But pretty much since noise reg's required bikes to be watercooled to reduce mechanical racket from the motor itself and required better exhaust design too, aftermarket exhausts appear to have done little to boost power. The last test I read was talking in terms of a couple of percentage points max. The average rider's not even going to feel that.
Is that all? Any teenager's moped did more than that back in the day. Even the restricted ones.