well have you straight piped your truck (taken off just muffler)? If so and you still want louder (like me! ) I'd suggest a magnaflow cat. Gave my truck deeper, louder sound. Well worth the money IMO. Got a part # 94037 off ebay and had it put on at a muffler shop (they only charged $60 labor to cut old one off and weld in new one) The cat itself was $85 shipped off ebay. This is about as loud as it gets staying legal.
Just a heads up. My year didn't have a direct fit Magnaflow so I bought the 94037. That was the wrong cat for my truck. The pipes coming off the manifolds go into a single pipe. I needed a SI/SO Magnaflow.
I bought it from Pep-Boys because they were the cheapest and I took it to a muffler shop to have it welded on. That's when they told me it was the wrong one. The guy had done hundreds of cats on our trucks and he even said this was the first one he'd seen that the 94037 didn't fit. And yes the cat on it before was the OEM original. Thankfully this shop was a Magnaflow dealer and he just exchanged the one I brought in for a SI/SO high flow cat.
This shop had a good rep and they lived up to it. For that I'll give them some free advertising.
Maganflow part number 23285 seems to be the way to go. Problem is I'm moving out of state Monday, and with Thanksgiving interrupting this week, it won't come in until after I move. Great timing! I suppose I could just take the cat out and hope I don't get in any trouble until I can get one shipped to my new house. The cheapest I found online was $141.86 at Hottexhaust.