Bolted on my GYT muffler and mid. Its a carbon fiber muffler and a titanium mid pipe. Wow. I'm shocked at the jump in torque. It added a lot of low to mid and still revs to the moon. I did no carb work, just bolted it on. I pumped up so quick on the track this weekend. I picked the muffler and mid on ebay, brand new; for $200. Its loud as hell too. If there is anyone left with a stock pipe on an 01 426, I will recommend it.