True cat-back

I've searched around here and across the interwebs and it doesn't seem as if any company makes a true cat-back exhaust system for our trucks. It seems that all the bolt on kits (Gibson, Borla, Banks, JBA, Dirty Deeds, etc) are after the resonator. In conclusion if you want a true cat-back exhaust you have to buy a Y-pipe too or build full custom. Anyone else confirm?

In the 1st gen it seems as if the Y-pipe is the biggest restriction in our stock exhausts, why don't these companies add a couple feet of pipe and a merge with flanges to meet the factory cats?

 

The y pipe looks terribly restrictive, but I replaced mine with a better one and nothing changed. No noticeable gain at all.

You can buy a y pipe like I did, or fabricate one, but you will need some level of fabrication to join it to any aftermarket cat back and at that point you may find yourself better off going custom.

If your piping is not in bad shape, I would recommend just swap the muffler for one you like. If that isn't loud enough, replace the resonator with straigh pipe. You'll be in all of $200 at most and get the sound you want. You won't really pick up power with a cat back anyway.

 

I believe @dirtydeeds will make you whatever you want if you give him a call. Anything is possible with enough

 

I get that, but the butt dyno isn't a calibrated instrument. I'm also not an engineer and no nothing of fluid dynamics or flow. But common sense says two crimped pipes merging into a resonator is a restriction.

I've got a plan and some dyno time booked tomorrow for baseline figures. By the time I get the parts together and put on, the dyno numbers wont mean anything. The after dyno wont happen until at least January. But I'm more interested in the shape of the power curve, and torque curve under 4000 rpm.

 

Correct, their full race setup with cats solves potential flow issues across the board. At a cost.