There's nothing out there on the net about the power curve of the f4i with coffman. I had done a run with the coffman on. It does lose heaps- have a look.​​​​​​​

Dyno printout of CBR600F4i with coffman exhaust

 

Thanks for posting but I can't read that printout very well. Is that with the baffles in? How much loss is there? I hate the thought of going back to a stock pipe 'cause the Coffman sounds so good!

 

Clicking on the link just shows me the very top of the page not the actual dyno at all.....

 

hi, this was with baffle. Btw. in one of the runs the exhaust was almost blown away, I had used a smallish rivet. so make sure your rivet is big and strong.
posting an enhanced version of the above pic

 

Sweet. Very surprised at the low number, even more surprised a slip on actually lost power.

 

 

Was there a run with the stock exhaust? If so, how many hp were lost? If not, is it possible that the baseline (i.e. stock setup) was lower than average to begin with?

 

Excellent point. Just because a stock F4i is around 95rwhp doesn't mean it makes that much on that particular dyno.

 

Hmm, I guess the only way to tell is to have a dyno run now. I'd be doing a run in Jan, will post the results here.
But that won't be with a stock exhaust. I now have a Yoshimura race can and really the setup is basically a stock F4i motor with FX/FY headers, linkpipe and can. So it's not really a stock setup.But I guess a run now should give you decent idea about how much stock is as I don't think an FX header and a race can can magically lift the power band if the base is this bad(assuming coffman didn't lose much, the bike was a pig even before)
Frankly, seat of the pant feel tells you a lot and that dip was really noticeable. You don't need dyno to notice obvious crests/troughs in the power band. Before the coffman I used to have a scorpion stubby exhaust with baffles not removed(with f4i stock header, link pipe etc)and the bike had good meaty midrange. After getting the coffman, the midrange was gone and that dip you see above was very very irritating. I am unsure if it was any better with the noise reducer out as I never tried it.

Wish you a happy new year guys. have a good one!

 

Thanks for the follow-up! Now I'm tempted to put my stock can back on this spring just to see if I can tell a difference...