i'm looking into getting a new exhaust/muffler and a high flow cat...i'm a little bit short on getting a new system so i was wondering what combo cat/muffler you guys think are best. i've got an '01 5.3l also is it really that much help to get the whole system or will i be fine with just a hf cat and muffler? thanks.

 

first off, you have two cats. They flow fine by the way, you don't need to replace them if you're going to be keeping cats at all. Even with longtube headers keeping the stock cats is not a bad option.

So you just have to replace the muffler. The least expensive way, if you're fine with the stock outlet, i would suggest would be to buy a 2.5" dynomax ultra flow single in/out. It'll sound nice, and you won't have to worry about drone.

Magnaflow is also a good brand. It's really up to you, just promise you won't get a flowmaster.

 

well i wasn't planning on replacing the cats but i think that one is busted on the inside. i have a really tinie sound coming from it at about 1k rpms. it's realliy annoying so i'm just going to swap em out. i've been under the truck as well as a few friends and everybody thinks it's coming from one of the cats. that's the ONLY reason why i was changing them. and you don't have to worry about FM's on my truck...i've been that route before.....

 

Magnaflow. I thought it was a 3" you need so it would slip over the factory pipe?

 

2.5 or 3" ?

 

The muffler shop I used for my exhaust only get mufflers with 2.25" inlet /oulet. My truck has dual 2.75" pipe, the inlet and outlet were expanded out to fit over my factory exhaust.

Current exhaust;
2 - 40 series flowmaster
dual 2.5" outlet, existing on the passenger side

I plan on replace the flowmasters with some Magnaflows.

 

I bought my gibson cat-back for @350.00. Just a thought. NO BLOWMASTERS!!!!!!!

 

Carsound makes decent cats. I think Magnaflow sells the Carsound cats also. I went with Magnaflow model number 94106. They are 2.5" in/out and are relatively short. I'm happy with them.

 

random technology makes good cats as well.

 

I agree with using either random technology cats or the cats from SLP. Those would be my choices for sure. There isn't much gain in going to high flow cats though. Keep in mind though that the factory cats are under warrenty for 8 years or 80,000 miles. If you fall into that I'd recomend that you just have them replaced under warrenty and use the money for the cats elsewhere, possibly buying a nice system such as a Corsa cat back.