Baja dune 150 stock muffer upgrade

[Johnny 5]

I have been wanting to up grade our muffler on both our dune 150s but cash is tight. I tried drilling out our first dune 150 muffler two years ago from stock inside diameter of 5/8 inch to 1 inch. With not knowing much about these buggys I did not think to jet up and it ran worse it sputtered and by the end of the day the intake valve seat fell out and the motor was done. So when we replaced the motor I also put a new stock muffler back on. Now with all the great info on buggy masters I know to jet up. So I have some bmx handle bars sitting in the garage and the tube inside diameter is 3/4 inch. I cut off a 2 inch piece and welded it to a washer that is 1 1/2 and welded that to the old muffler. Now it has a bit more flow and still has a decent amount of back pressure. Wont know if it made much of a change because we are 2 hours from any decent riding area. I jetted up from a 114 main to a 120 35 pilot and air fuel screw about 2 turns out. It runs good up and down our short street, we will find out next weekend on our first ride. If this works I will modify the othe buggy muffler. This way we can test both mufflers back to back and see if it helped. With the stock muffler the jetting up just kills the power. I tried a 125 120 117.5 and even the 117.5 boggs the engine.