I just put a 4" Magnaflow cat into my MBRP straight pipe. I was told it would eliminate the vvt hiss, make the tone a little quieter, I would be able to pass emissions no problem and not sacrifice the power of the straight pipe . If this were the case it would be well worth the $260 I paid for it. It seems a little restrictive and the hiss is still very noticeable. If you need a cat in there for emissions you could clamp one in and have a straight pipe to clamp back in place afterwards right? Maybe have some pipe welded to the stock one to make that work if you still have it. I would not recommend the Magnaflow unless you need to have it on there permanently, it is much smaller and less restrictive then the stock one. It is not the proper solution for my problem though.
I need one to stay in full time and I already have the cat delete pipe in. I'm in CT and I travel a lot to NY, RI and MA, all of which are stringent when it comes to checking. My buddy got pulled over without one, $10,000 fine and the vehicle had to be parked and he had to find a ride home, get the truck towed and buy a cat. I'm trying to save the hassle of that
4 inch I.D. all the way through to the tail pipe, but there is a perfect spot to cut a piece of the cat delete out and weld the cat in. Its right between the two tranny cross members since the pipe is perfectly straight there.