Longer exhaust always sounds better in my opinion, and try to get at least 3 feet of exhaust after the muffler. I run the stock manifold, I split the downpipe so that it remains 2 pipes, one is cylinders 2,3 and the other 1,4. 1-3/4 pipe back to two thrush welded mufflers, and back down to 1-3/4 pipe over the axle and out the back. It actually sounds pretty good, and doesn't drone