CatBack Systems for FI

Just wondering what others are using for catback systems on their forced induction engines. I'm considering a 4" Mufflex system.

Cant go wrong with that ... Im about to be in the same boat as you. Im buying a D1SC, and need a new muffler ... I thought about ripping the cat back off, putting a Flow Master Race Muffler on, and dumping it at the rear axle but ...

There are a few guys who have done pretty well with a hooker cat back and FI. They seem to flow really well for a cross flow.

Borla with an open plate is good.

And you cant go wrong with a GMMG.

I would imagine a Loud Mouth would flow nicely too.

I have GMMG... Anything with a good straight through design (no flow restrictions) is good... The bigger, the better.

I will be using LM with bullet muffler.

Anyone do a before and after dyno of a good catback versus true duals on a blower/turbo car?

Just wondering if they are as "needy" of a highflow exhaust as a NA motor is ...

I run SLP TOTL
Straight through design and awsmoe sound

Just wondering if they are as "needy" of a highflow exhaust as a NA motor is ...

They are actually "more needy" ;) because there's more air to get out of the exhaust. You'll pick up more power going to a good catback with a FI car than with a NA car.

There is a thread about header design in the Advanced tech forum. rskrause posted a really good article on exhaust that you may benefit from reading. It was enlightening, at the very least.

Jeremy

Thanks Jeremy, was a worthwhile thread.

I'm considering a 4" Mufflex system.

Yuck. Both mufflers they offer suck a fatty. Spintech and Flowmaster are garbage. Get the Mufflex piping and install a Magnaflow muffler. Also, I had good luck with a 3" Aerochamber cat-back up to 550 rwhp.

Guy I spoke with wouldn't sell just the piping although that's what I wanted originally. What's wrong with the Spintechs? I was also considering the Corsa. Since I'm looking for about 600RWHP, I want a good free flowing system.

Yuck. Both mufflers they offer suck a fatty. Spintech and Flowmaster are garbage. Get the Mufflex piping and install a Magnaflow muffler. Also, I had good luck with a 3" Aerochamber cat-back up to 550 rwhp.

So Mike, what I think you are saying is that you don't think the Mufflex mufflers are any good? :D

Jerry

So Mike, what I think you are saying is that you don't think the Mufflex mufflers are any good?

You're pretty good at reading between the lines ;)

I've had way too many dyno and track experiences with both SpinTech and FlowMaster. In my opinion, if you gain more 2 mph or 20 hp when you remove a muffler, then the muffler is no good.

Mike, you ever do a dyno pull with your hooker, and then without? To see how much that muffler was holding you back at that 550RWHP level?

Mike, you ever do a dyno pull with your hooker, and then without? To see how much that muffler was holding you back at that 550RWHP level?

Yep. 545 rwhp through the full 3" Aerochamber cat back. I removed it at the Y-pipe and it made 550 rwhp. Results weren't so great at the 700 rwhp level.

Spoke with Magnaflow tech. Based on that and engineermike's comments I'm gonna use a Magnaflow either 3.5" or 4" system. Should be a minimal restriction since its a straight through design.

lol well, at 700RWHP ... That could kinda be expected.

How bad was it? Just curious?

I am trying ot figure out what i want to do now, for my soon-to-be blower car. It will only be on about 7PSI until I build me a forged shortblock but ...

Thinking of taking the catback off, running some type of small, unrestrictive, straight-through on it, and dumping it, at the rear axle. Catback only going on for I&E ... Since my boss wouldnt sticker it for me I dont think, with it dumped at the rear axle.

lol well, at 700RWHP ... That could kinda be expected. How bad was it? Just curious?

It's hard to say, exactly, because the boost level on a turbo is backpressure dependent. Remove some backpressure and the turbine speeds up and makes more boost. I can tell you this, though - at 700+ rwhp, when I removed an Aerochamber and installed a Magnaflow, the boost went from 18 psi to 24 psi with no adjustments to the boost controller. Also, the endwall on the inlet of the Aerochamber was bulged out from internal pressure and heat.

Mike

What kind of magnaflow are you running now? Just a regular magnoflow catback, or some custom set up?

If it was the catback, I have to say, WOW. I never realized they had that kind of free-flow advantage ...

also remember that every bend the exhaust goes through is a restriction. something exitting in front of the rear end will most likely make more power than a rear exit catback.

What kind of magnaflow are you running now? Just a regular magnoflow catback, or some custom set up?

Mufflex 3.5" piping with a Magnaflow muffler. The 12909 bolts right into the Mufflex piping with no modifications. I'd say that this exhaust combo would be hard to beat.

I originally planned to run a 4" Mufflex with a Spintech dual exit, but since my tank is sumped, the option of running any traditional 4th gen F-car exhaust system went away.

I ended up using the Mufflex 4" stuff, but run a single 4" exiting out the back with two bullet mufflers in line and a turn down now.

Hmm ... I am really impressed. I wonder what the difference would be between that, and a magnaflow muffler on 3" piping ...

Its gotta choke it up a good bit more.

I think I am going to get some sort of free flowing single muffler, and hook it up at the Y, then single pippe dumped at the axle.

Saw this setup for some of you:

http://www.ls1tech.com/forums/showthread.php?t=585223

Im gonna make a custom "LM" for my car. They have 3" to dual 2 1/4 im gonna have a 4" off the downpipe to dual 3" pipes. Shouldnt be as loud as my car was with long tubes and the normal LM since its going through a turbo now

Not sure if this is a good comparisin but I originally had a magnaflow 3 inch system on my car. It was so loud it made me sick.

I have had a mufflex 4 inch with the spinteck muffler for 2 years, running through 2 3 inch magnaflow cats its just loud enough to live with. I had to change exhaust just so I could drive the car.

Have not run car without exhaust but through cats it made 657hp 590tq at wheels.

John

John, Which Mufflex system are you using? Single 4" outlet or the dual 3" outlet?

i am running GMMG on mine :D

John, Which Mufflex system are you using? Single 4" outlet or the dual 3" outlet?

Dual outlet 3", car is louder at the front than the back:) ever since I put the T trim on.

Originally with the magnaflow I had to make sure I was coasting if I drove past anyone that could give me a ticket.

John

Purchased a mufflex 3 1/2 system with a spin-tech single outlet. There was alot of back pressure and the pipe was blown off many times (383/ D1/ 72# injectors). So, I made my own pipe with a QTP cutout dump @ the right rear seat area. I retained all of the mufflex down stream stuff. That solved the back-pressure problem. The engine would just not rev with all that restriction. Still run the spin-tech when I want to be real quiet. Spin-tech did not work well with the blower.

...So, I made my own pipe with a QTP cutout dump @ the right rear seat area. I retained all of the mufflex down stream stuff. That solved the back-pressure problem. The engine would just not rev with all that restriction. Still run the spin-tech when I want to be real quiet. Spin-tech did not work well with the blower.

This always intrigues me. Why not replace the Spintech muffler with a $110 Magnaflow. Then, you get all the power, all the time, without flipping s switch, plus it's quiet.

Do you use the 12909 muffler or the race muffler?

(the add in the link was race muffler and you posted/wrote 12909 muffler here)

I'm thinking of getting a 12909 but I'm worried that it should be a restriction and on the other hand I think a race muffler 14151 would be to loud for the steet......

/N.

Do you use the 12909 muffler or the race muffler?
. . .I'm thinking of getting a 12909 but I'm worried that it should be a restriction

I use the 12909. Not sure how I posted the wrong link, but here it is again:

http://www.magnaflow.com/02product/shopexd.asp?zone=main&id=1070

Unless you're making over 1000 hp, I highly doubt the 12909 is a restriction. I pulled mine off and it makes no difference at all.

Mike

How does it sound at idle and at WOT?

any soundclips/movies?

/N.

How does it sound at idle and at WOT?

I don't have any soundclips, but I can say that it's much quieter than the old 3.5" Aerochamber that I had.

The QTP was $154.00 for a single 3 1/3" unit. It takes about 3 to 4 seconds to open. Also, noise can be limited by opening partially. You must use care when opening and closing preventing current overload the QTP electric motor. The switch is a momentary, so, short on-off signals seam to be the best for me, and, listening to the exhaust note. Also, with the engine off, you can hear the electric motor load up when @ full closed or open position. This is one feature QTP and others don't tell you, but, now I see QTP has something else for better control (of course, more money). I just tried this to see how it would work, and, it looks to work the best for me. My next move was to use a 4" cc insert into a 4" pipe and fabricate my own muffler. I got alot of time this Winter.

Ordered the 12909 from summit.

Do you think my 3.2" interm. pipe will be enough or should I step up to 3.5" all the way?

Just recently revised my exhaust system per Engineermike's recommendation. I now have Hooker LTs, Mufflex 3" Y pipe into Mufflex 3.5" catback but using a Magnaflow 12909 muffler. I really like this setup. Sounds good IMO and not too loud. Thanks to Engineermike for the suggestion :thumb:

Thanks to Engineermike for the suggestion :thumb:

No problem! I gaurantee that's about as good as it gets for an exhaust system!

Can anyone post a sound clip of the 3.5inch mufflex set up with the magnaflow muffler?

I run SLP TOTL
Straight through design and awsmoe sound

Do you have any videos of your car? I'm interested in how it sounds.