Well my cat fell off and the 3" downpipe was installed before I bought the truck. Is the stock muffler restrictive?

 

It's a straight through style. There's a pic of the inside floating around here somewhere.

 

You can leave it be if you want

 

In my opinion its still restrictive. The exhaust will swirl around in there causing a little back pressure. I've done it both ways, EGT's were a little higher with it also.

 

Thanks guys, I'm not pulling or carrying any loads. I do drive 75 mph sometimes though. I guess I'll let it be and save a little money for now.

 

I've done it both ways, straight pipe and stock system and I can't tell any difference performance wise either way. The turbo whistle is nice without the muffler, but it is a much quieter ride with it on there. I'm running a 3" DP into no cat, and the balance of the stock system right now. It sounds pretty decent IMO.