I had the Miltek none resonated cat back system.
Bought it on here for £450 I think.
Sold it one month after fitting. In my opinion I would keep stock until it rusted through rather than remove the OEM item for one of these.
I then bought a full TBE BCS unit. not the power valve one, but 3" all the way through.
I love it. I like simplicity so kept away from the power valve concept as in my eyes there is something that could go wrong here. (It may not but I like longevity!)
Get another insurance policy and a decent unit. Am in York if you want to here it for real!'