Just the box mods will show minimal increase, but combine that with a good pipe, PC, pair removal, and filter, and you'll pick up around 12-18hp at the rear wheel.
yeah, but which one did the deed?
I think the airbox mod is crap.. just changes the power curve a smidge the best I can tell..
give up a little down low and put it on the high side..
i'm no expert... thats just how it looks to me.
the whole reason for the flapper is for increased torque at low rpms from what I've read.