that's not strictly true. Depends entirely on the engine set-up.
The horsepower argument comes from the belief that a "freer flowing" system must be better, but that's far from ever being the case, it totally depends on the engine setup. I'd suggest on a newer bike/car the chances are far more weighted in favour of no effect or power loss, simply because a reduction in back-pressure in the system fucks up the fuel management a little.
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 23 Jun 2010, 10:15, 1 reply)

Cars yes,
try telling all my bikes to keep the front end down with race cans on though! Emmisions are so stringent, we regularly see (only) around 5 bhp increase with pipes. (Manufacturers are restricted to 5% increase for TUV regs.) Admittedly, you'd have to be bloody fast to tell the difference, it's only my v-twins which really turn on the extra power.
( Blind Meach Cautiously optimistic, Wed 23 Jun 2010, 13:24, closed)

No idea
if the race can on my good old 1000RX improves performance, but it sounds sweeeeet. I dare say it has saved me once or twice too, on one occasion I did see a dizzy old dear about to T-bone me, she could definitely hear me, but hadn't got a fucking clue where I actually was (on the road, my right of way, well within the speed limit). Thankfully she stopped for a look around to find the crackling beast which was making all the row.

That said, it must really piss the residents off in the Peak District etc, listening to the Power Rangers blatting round those roads every fucking Sunday when they are trying to sit in the garden and read the paper.
(Rsoles, Wed 23 Jun 2010, 15:38, closed)

In some cases I'm sure
but just cutting the baffles out ain't the same as putting a race can on, is the point I'm making. Race cans will probably be at least vaguely balanced for the engine they are going on.

Actually on a car, race exhausts are usually a waste of money as a fair bit of the restriction is in the manifolds, so unless you change them too, you're just wasting power on noise.

I've generally run classics and I'm still astounded by people who chuck on wide body carbs without changing the inlet manifold and think that'll speed things up. Genius.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 24 Jun 2010, 9:16, closed)

Absolutely right!
I love seeing saxos with an exhaust larger than Jordan's twat.
( Blind Meach Cautiously optimistic, Thu 24 Jun 2010, 9:23, closed)