I installed the DT catback exhaust and it was the worst thing I did to my cruiser. I had to replace the muffler due to rust around the seams.
The original toyota resonator and cats were fine. Everything bolted up nicely except for the fact the DT had forgot to cut grooves into the female portion of the pipes, meaning the pipe would not compress when being clamped onto the male section. I called customer service and they literally told me to cut the grooves myself or take it to a muffler shop, and that they would not help me. It was easy enough to cut the grooves in, but was definitely disappointed with their customer service. That aside, installed everything and went on a test drive, i could not believe the amount of drone the exhaust created, anywhere from 2000-3000 rpm, to me, it was intolerable... my rear view mirror would vibrate, it was that bad.
I drove it around for a few days, then went to a muffler shop where I had them weld the stock resonator on. much better now. Still louder that stock but without the insane drone....