has anybody tried drilling an additional hole at the bottom of the baffle beside the existing tube? Well, I did... and it was calculated based on the dimensions of the exhaust port. The header should have a diameter of 22mm and the exhaust tube 16mm at the most. Existing tube only measures 8mm. I could'nt pull out the baffle so I think this is the next best thing to having a tuned pipe. I used a 3/8 brass male coupling from Ace hardware and redrilled the bore to have 8mm, drilled a 10mm hole beside the exsiting exhaust tube, then installed with some muffler glue. Easier mods than removing the baffle and drilling more holes. It's not that loud, but pulls a lot better and definitely more responsive. Four stroking is mininmized if not eliminated.