Just did the muffler delete on my 19 TB Custom with 5.3 and 6 speed, it sounds awesome too! I left the flapper in and haven't bothered covering any of the resonators. I spent a lot of time reviewing comments and watching videos, but to be honest, the muffler delete alone was exactly what I was looking for. It's quiet on highway or just cruising, but if you hammer it it's loud as hell...especially on a cold start.