Hey all, so I've been pondering this for quite a while now, and thought I would drop the question to you guys. I have a 2004 F4i with about 10,500 miles on it. I put on a two bros slip-on last summer and noticed a bit of a power difference, a HUGE sound difference, and a bit of an "engine smoothness" difference. One thing I noticed with the stock exhaust is that it ran REALLY smooth. Super smooth throttle response, no backfiring on deceleration, etc. Now that I have the two bros on there, it seems like the motor runs a little more rough. I.e. backfires on deceleration (a bit, not a huge backfire, just a little pop), runs a little rougher unless I'm WOT, etc. My friend has the exact same bike with a yosh slip-on and his runs super smooth like the stock one, but I think it's not quite as radical of an exhaust because it is quieter as well. Question is, do you think this "roughness" I'm experiencing with the two bros can be cured (or partially cured) after re-mapping it? What do you guys think?

 

THIS MAY HELP....
https://cbrforum.com/forum/f4i-main-...pc-iii-125362/

 

Thanks xtreme. Sounds like the throttle response will be smoother, but my throttle response isn't what's lacking (my problem really isn't how the engine runs, just more how it sounds). Power delivery on my bike is great, no dead spots or anything (actually I think the two bros improved the dreaded 4k rpm dead spot it seems F4i dyno sheets have) I'm just wondering if something like the PC III would make the engine sound smoother (eliminate small backfires etc).

 

You should try doing the PAIR removal. it is supposed to help with backfiring on deceleration. I woula assume that a PCIII would help too but I cant say for sure but I would think so. you could always get a dynotune too if u get a PC