I've been on this whole 4" exhaust kick now for quite some time, and I really want to just get one. I've priced Mufflex kits and they are outrageous, sometimes even used. Plus the choice of mufflers lacks something to be desired. Spintech mufflers, while some claim are the best sounding 4" mufflers, have a bad rep for killing HP. The flowmaster has good and bad qualities as well. But what you only hear good things about is the 4" Magnaflow. Trouble is, no one makes one. You basically have to either call up Mufflex and have them make one for you, or take your own mufflex setup to a shop and have them hack out your muffler and put it in its place.

So I had to wonder: Could an exhaust shop just make one? The shop that I use has always got full blown race cars lined up in its bays. They create cages, do metal fabbing, and complete tear downs/ build-ups for people. They also work with diesel trucks quite often. I know they would have 4" mandrel sections in stock.

How hard is it to route a pipe that big over the axle? I am wondering just how much it would cost to have them make me a system featuting a muffler that I bring them.... I think I'll give em a call tomorrow.

BTW, this is the shop that hacked out the merge in my pacesetter Y and installed the 4" flowmaster y. For that job, I supplied 2 V band clamps (which they put on my header collectors), sold me the used 4" merge, cut out my old one, fabbed it up using pre-made mandrel bends, fixed a few leaks, and charged me just over a hundred bucks for everything including the merge.

I supose I could even print out pictures of Orangeapeals old 4" magnaflow system and show them just what I want.

 

Just curious, but why are you trying to go to a 4" exhaust system anyway? Maybe If our cars came w/ a 427 in it, I'd understand. With that flowmaster merge you have in your Y pipe you already are doing better than most people as far as flow is concerned(at least me.) Dont get me wrong I'm not trying 2 sound like an ******* but a 4" system is overkill unless u are making some BIG power.

 

Oh sorry, I am hoping to go with a D1SC in the future. Yeah, this is one of the first things that I wanted to do in preperation for FI. Plus, the 4" setup makes a really deep sound, kinda like a big block car.

Also, a 4" pipe is roughly 11% smaller than two 3" pipes.

 

Oh ok cool. Be prepared to spend some $$$. Forging the LS1 is not cheap, but almost a necessity when FI is involved.

 

i built a full 4 inch from turbo back. made it like an SLP loudmouth. with dual tips out the back too. also built another one that was dumped before the axle.
4 inch can be done. it is tricky lot of work. i did all mine in mandrel bent too. so i cut and peiced them all together and fully TIG welded them once they were tacked together.

 

If Mufflex can do it I don't see why a custom fab shop shouldn't be able to handle the job. As long as they're good, that is...

 

https://ls1tech.com/forums/showthrea...852&highlight=

found some pics of the one that i built. added stainless tips since then.

 

i made one

 

Freakin awesome. I wonder what the piping and labor will cost? These are some good pics to take with me. I will definately have it turn down at the end of the tail pipe.

 

3.5-4" systems have a very unique sound due to the size of piping. I understand why you would want it, I have a 3.5" sysytem myself. My advice is this; either find a very reputable exhaust shop by you that can make a system that you want or call up Mufflex and talk over a system with them. I know this first hand; Mufflex made my system and it is outstanding. I have personally seen exhaust shops(Midas, etc) attempt to make large systems and absolutely slaughter them, which in turn made the owner either modify the system or get a whole new one.

Here's some pictures of my system.
https://ls1tech.com/forums/showthrea...082&highlight=

 

AKAFRED: That looks AWESOME. Wow. I'm saving those pics for when I tackle this job.

 

that is a good pic , props . unless you know someone and still if you do depending on the setup they can be up there . though if you are going fi do it to it . there is a chart from a while back talking about about what aize pipe is good for what kind of power . if i can find it will post link ,

 

Well, scratch that. I just called them and they said that it would probably be cheaper to just buy a new one! HA!! Oh well. I guess I could always pick up a used kit and then at a later date have a Magnaflow put in.

 

I have the 4" Mufflex Magnaflow system and I love it. Here's my thread talking about some of the pros and cons of this system. I didn't gain any power over the GMMG even at 500+ rwhp, but IMHO the sound quality was improved so it was worth it. (Please don't turn this into a GMMG vs world fest).

https://ls1tech.com/forums/generation-iii-external-engine/899824-gmmg-off-4-mufflex.html

 

Nice. Do you have any videos of it its idle and a few revs?