Here is a pic of the y-pipe I made to connect to the 4" mufflex exhaust. It's only tacked together right now, but I will fill the remaining joints and paint the whole thing.
Here's what I did. I chopped off the 3" portion of the Hooker SuperComp y-pipe (you can see it in the picture...don't want a restriction there do I )
I ordered some of the pre-bent 2.5" pipe from Jegs. I bolted the two pieces of the y-pipe to the headers and went from there. Cut the pipes to appropriate length and angle, lined them to clear everything, and tacked them together. They run into a Flowmaster dual 2.5" to 3.5" y-collector that I expanded to 4". The "y" goes into a 4" Dynomax Bullet race muffler. (These things are straight through with little holes to go into about .5" of fiberglass, the whole thing is 5" round.) The muffler sits where the cat used to be. (you guys who want a loud exhaust, stop here ) From here, the muffler simply attaches to the 4" Mufflex system. Anyways, I wanted to knock some loudness off before it hits the SpinTech cross-flow race muffler and dual 3" pipe to 3x4" oval stainless tips at the back.
I think this sucker really ought to flow some air!!
Maybe the 'ol 383 can exhale now:lala:

Oh yeah.....and it all fits wonderfully and clears the subframe connectors and only set me back about $90

 

Looks good. I want to hear some sound clips when you get it done.

 

Hey Dragula,
you are just a few steps ahead of me.
I have a 7500 rpm 377 CI SCCA race car that I am redesigning the exhaust for as the earlier system wont breathe the new motor.
I have 3" coollectors on the super comp long tube headers and need to bring them into a single 4" but,
If you lower the diameter of the header collector to 2.5 inch then aren't you basically defeating the purpose of having the 3" header outlet?

I have a flowmaster collector from the old exhast and I'm thinking about using it as a model, need a rectangle "can" that can take two, 3" flanges, (like cutouts) one one side and a single 4 inch flange on the other, and bolt the pipes to it.
question,
Are 4" flanges available to bolt up to?

What did you pay for your 4" system and who has the best prices?
Thanks
Evan

 

The only ones I know of are Mufflex.
I paid $660 shipped for mine with duals, I believe the single outlets start at $525 before shipping.
The SuperComps have a 3" collector, but it narrows down before it enters the y-pipe, so I am really not hurting it at all. Besides, the collectors are so short that it's still going to be the individual exhaust pulses pretty much dumping straight into the y-pipe.

 

Awesome Y pipe!! I'll be bringing over the same piping from Jegs and a Flowmaster 2 to 1 pipe so you can help me out with mine. just kidding. You did a fabulous job though.

 

Thats very cool man, I like it when people step up and try things like that themselves. I would but... I don't know how to weld or have access to the equipment to do it.

Besides killer airflow you'll have the adv. of the fact that the bullet muffler kinda looks like a cat... so if somones looking... ya know? Plus they don't cost too much either.

 

Finally got the thing fired up today....sounds mean. Real deep sound, yet not too loud. I think the straight trhough Dynomax helps a bit without killing the airflow. Now I just need to figure out the idle tune so I can drive the thing.

 

ttt, just wondering if you have any sound clips or anything yet.