Stock down pipe with 4" cat-back system?

[Erwin8r]

I'm going to upgrade my exhaust to a 4" system with a magnaflow muffler. Will my stock down pipe flow well or should I upgrade to 3.5" or 4"? Will my EGT's be affected if I keep the stock down pipe?

Advantages? Disadvantages? I don't have much in the way of performance mods, other than an AFE intake.

Will be doing an SCT and gauge/monitoring package very shortly after the exhaust... Thx.

[kinnisoj]

Im running the Diamond eye 5" TB no muffler at all. As far as egt's Im hoping to get my probe into the truck today so I cant tell ya about that. But I can say as far as installation, very easy no sweat,sound, awesome wish it was louder. Thats my .02

[Erwin8r]

Originally Posted by kinnisoj

Im running the Diamond eye 5" TB no muffler at all. As far as egt's Im hoping to get my probe into the truck today so I cant tell ya about that. But I can say as far as installation, very easy no sweat,sound, awesome wish it was louder. Thats my .02

But what size is your down pipe?

[portcity_gt]

I'm running a stock down pipe, I'm almost positive it's 3.5 stock. It then Y's out into 6" side pipes, I havnt had any trouble.

[Erwin8r]

So other than size with a larger aftermarket down pipe, what are the advantages of an aftermarket down pipe--especially if one goes with a 3.5" down pipe?

And what helps lower EGT's--the down pipe or the over size exhaust with no cat?