I have changed out my downpipe and have a cat delete. I am trying to decide if changing out the rest of my exhaust from the stock 3 1/2" to an aftermarket 4" will make much difference on the EGT's. Also What brand have you guys had good luck with? I was leaning towards a Diamond Eye but I wasn't sure. I was going to try and keep the system with a 4" cat delete pipe so I can add the cat back to the system if I had to start dealing with emissions again.