flowmaster has a really nice looking merge collector that will Y two 3" pipes into a single 4". I remember my old pacesetter Y was actually a T pipe lol.

 

I have used that flowmaster merge on 2 or 3 builds now and man does it drone like crazy. Gets the job done though.

I wonder how hard it would be for ARH to make the 2" (or maybe even 2 1/8" headers) with a 4" collector...

 

4" collector... daaang.

Interesting note, even the COPO uses 2" primaries with 3" collectors.

 

Anything worth doing is worth over doing

 

I'd bet willing to guarantee a nice increase in power going from an 1.875" primary to a 2" primary. After that, it's pretty much up to you but these would be the options I would consider (1 being the best and so on so forth):

1. with the 2" header, adapt it to what you already have, and just add a cut out near the flange.

2. I believe you can get a 2" kooks on that truck with a 3.5 collector, after that, a dual 3 or even 3.5" system

3. Keep the 3" Y (or 3.5" Y if new headers) and go to a single 4" system with a very short Magnaflow muffler dumped before the axle.

To me, the single 4" big power trucks sound the best so I'd maybe do that but still add in the cut outs.

 

I've been running a 2" Kooks with 3.5" collectors with some 3.5" stainless extensions to keep the O2's clean. Sell the X-pipe for money for something else. Scavenge tuning for blower deal is a waist of time.

My new setup will be a 2.25" primary and a 4.5" or 5" collector coming out the side of the truck somewhere.

 

With boost scavenging becomes a non issue under power, its relevant at low throttle and cruise but your cam valve events will determine how relevant. What are the cam specs? I am running a single 4" with a cutout, I really like the sound of it but had to run two magnaflow straight though mufflers to tame it down. (I don't want it obnoxious.

Measure your back pressure at your collector and see what you have, that will give you an idea what you are working with.

Also like Blown has in his pics, V Bands are you friend. I used them on mine and it makes stuff much easier. With a single 3" before I had 12+psi back pressure, with 4" I have none.

 

This is on my 69 camaro so a y pipe makes no sense. The system will be very short compared to a truck. 226/246 118+4 in a 408 with ls3 top and a blower.

 

Stew on your Camaro I would just do dual 3" without a doubt.

 

What do ya'll think a 6.2 would put down with a P1 with either one of these cams that STOCK48 spec'ed me.

221/233, .575/.595, 112 lsa or 221/236, .575/,598, 112 LSA

I know a P1 is small but that might be what I have to run price wise "used" to convince the wife to let me get into the boost game LOL. I'm going to cam it this winter then go ahead and do injector and MU1847 AC DELCO pump. The boost will come next year when it's paid off. I just need to figure out which cam and if I want a 112 LSA or 114 LSA, this will be my first cammed vehicle and first time trying to swap a cam. And just so you know it's not an all out race truck it needs to pull my boat every weekend.