exhaust systems

[beerbear]

what kind off exhaust systems are people using on the gy6 howit for performance its on a 3206 spider box? what do you think of the bd system?

[xlint89]

I have a FMF slip on muffler installed on the stock header pipe. (cut off the stock muffler)

It works quite well. However, it is pretty loud just so you know.

Just for cheap perfromance gain, break that exhaust tip off of the stock muffler. That will open up the exhaust a little bit, but you will most likely need to bump up the main jet in the carb.

[Johnny 5]

I cut the 5/8 tip off the muffler on our dune 150s and drilled it out a little to put a 3/4 inch tip on. Used a 2 inch long pice of handle bar tubing from a old set of bmx handlebars that were in my garage. Welded it with my hobart 125 welder on the lowest settin. Didnt want to go to big and loose botom end torque or make it too loud.
I did jet up from a 114 main to a 120 main also with a 58.5 srp piston kit. Would like to try a better muffler some day but for now this works a bit better than the 5/8 muffler tip.
A couple of years ago drilled the muffler out to 1 1/4 inch and it ran very poor and the intake valve seat came out and bent the valves and locked up the motor, because of not jetting the motor up from the 114 main, and overheating the motor.

This worked for me on a budget,3/4 tip to reduce some back presure without getting too loud so the neighbors wont get mad when we test and tune on our street. We are 2 hours any direction to go riding so most tuning is in the driveway
With the drilled out muffler it sounded like it was trying to hard to be cool.