Originally Posted by
marty
Just been reading an interesting article in Superbike mag about OEM vs aftermarket exhaust - the biggest advantage was weight, not HP increase.
Varies a lot with different models of different bikes, mind you.
I don't think it's possible to make a blanket statement that aftermarket exhaust systems do or don't give more power. It's entirely dependent on the details of the engine in question and the other tuning changes that are made when the exhaust system is changed.
I don't have dyno data for my K7 GSX1400 when it had the stock exhaust, but when I had it removed and replaced with a 'fairly open' TBR can, top indicated speed with me on board went from 230 to 250. That's a serious horsepower increase.
But fuel economy turned to shit. Went from averaging 300km per 21L tank down to about 240.
After a fuelling remap on the dyno by TripleZee Cycles in Manukau, the fuel economy is the best it has been; I got 345km out of my last tank.
So some bikes will probably be greatly improved by aftermarket exhausts, others not so much. The K6/K7 GSX1400s are probably extreme cases; I doubt your average bike would do so well from having the stock exhaust thrown away.
Either way, I don't think there's any point chasing performance without measuring it on a dyno. Too many bikes have been fucked around with and most probably made worse, not better.
kiwibiker is full of love, an disrespect.
- mikey
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