what I have is a 5.9 99 1500 quad cab 8'bed

the situation is............I want a 3" single out the side. All the exaust shops(yes all 23) in my area keep trying to talk me out of it because "you only have 2.5 inch pipe to the cat so you are wasting money with 3 inch pipe"

Is there any merit to this statement would I be wasting money with 3" pipe I asked about a cat with a 3" out put and got the same statement execpt it was the y pipe instead of the cat.

My thoughts are biger pipe no mater where it starts should help flow right?

Headers would not work for me as they are not legal and I dont really want dual exaust either. Is there a solution I am not seeing or are the shops just not wanting to deal with 3" pipe?

Any info would help alot thanks guys.

 

why do you think you need more flow?

 

its still stock and I want to add a 52mm tb

 

52mm = 2.0472441 inches
The way I see it, you'll have one inlet of 2.05 inches and you'll have one outlet 2.5 or 3 inches. Even with the expansion from heat and the content of other byproducts, I still wouldn't think you'd need more than 2.5. All the performance systems I've seen is 2.5. Also, you're not compressing as much air as a diesel. I think the bigger issue is the bends in the pipe. If you have a 2.5" and at each bend it necks down to 2.0", you will have a restriction at each and slow the flow. The other thing would be where the gases are blocked (cat, muffler). Stock cats are about as good as the performance ones and a new muffler will outflow the stocker.

 

So you think my stock exaust is fine aslong as I get a freeflow muffler?

 

yeah, you wont see any difference by putting 3in after the cat. you will just spend more money on something you wont see any gains from. although a lot of people do the same thing (more money for no gains) but id just go with a 2.5 with a 3in tip or bigger if thats what you want. personally i think tips over 3in look too much like the fart cans you see on all the imports. good luck and let us know what ya go with

 

the biggest diff in the stock exhaust comes from #1 headers, #2 free flowing accessories (cat, muffler) I found when I redid my exhaust that my cat took a dump, and just replacing the exhaust from that point made a big diffrence.

 

I just put a Flowmaster Force 2 cat back on my truck and a magnaflow cat that had a 3" outlet and changed the pipe between my cat and muffler to 3". It sounds aawesome and I notice a slight differance in power.

 

The bigget problem with the stock exhaust is that, from begining to end, it is stock exhaust. Try replacing the factory Y pipe. I would replace that and gut the cat before spending any major bucks on your exhaust.