...it's simply a space problem. The virtually straight through 3" system is what's critical, maximum HP on the track being the paramount concern. On the 'quiet' side then we only have yay much room to work with, and while yes we could have built it to also be 3" with some super quiet muffler, why bother? The stock 2" system is free so first we'll see if it works good enough (or if the motor will generate enough PSI to blow it up ;-).