Mufflex y pipe with 4" catback. Not cheap though. Otherwise mufflex y pipe with a 4" muffler on it, wont get it out the back of the car though. Fwiw I use a pair of dynomax ultra flows right off the collectors on my lt1, its not too terribly loud. But I have relatively low power

 

If you want a system out the back from what I've seen Kooks is the best but it's pricey & only works with certain torque arms or crossmembers but I guess the fit & clearance is good, if your car is lowered Kooks is probably the best off the shelf system but I'm not sure they work with headers other than theirs.

Depending on your power level maybe Ebay or TSP if you don't mind turn downs before the rear but they work with only certain torque arms too.


Been trying to decide on a new exhaust for 1 of my cars, it had over 500 rwhp with old SLP 1 3/4 & home made 3" duals that dump before the axle, it's not lowered & clearance sucks so I may just do 1 7/8 with ORY & Magnaflow since I already have it & don't have to worry about torque arm choice.

 

me and a friend made my 4" exhaust. had the flowmaster y pipe/merge with a 4' outlet and just got some bends and a straight through muffler and just put a turndown at the end of the muffler in the crossflow stock location. it only loses less than 5 rwhp compared to open headers. that is with 525 rw so i am guessing a more powerful setup would start being a restriction but no experience to weigh in on that. a set of 3"true duals would be sweet but using turndowns is louder than i like and routing over/under the axle i am sure would be no fun.

 

Thanks guys. I've got the BMR short torque arm, with the cross bar that welds to the sub frame connectors. So the TSP true dual is out. It has bullets right off the muffler now. That's too loud for me. I was thinking Magnaflow too, or the mufflex. I guess I put the magnaflow on it, then dyno it, pull I loose on the dyno and see if it picks up any. Then add a cut out if it does.

 

I saw someone that had made a nice system, believe it was on ls1tech. It was a 3" into 4" Y with the flowmaster merge, bullet muffler right off the back of the merge, into a 4" cutout, then necked down to the stock cat back. Really quiet with the cutout closed, and just a 4" bullet in the way with it open. Kinda best of both worlds, just gets heavy with all that stuff

 

Use to have a similar set up to that just without the bullet.

Picked up nearly 40hp with the 4" cutout open. Car only made 440rwhp also.

Was an awesome set up. Super quiet closed and race car loud open. The exhaust weighted a metric shit ton tho.

 

I have dual 3" merged to a single 3.5" running through a single Magnaflow muffler. I don't remember the part # but its the biggest muffler I could fit in the stock location. No cut out. This is a grudge street car that I drive anywhere. Very quite at idle and part throttle. Sleeper for sure. Sprayin a decent shot of nitrous through it all.

 

Any chance you can post a picture?

 

KOOKs, From the heads to the tail pipe. Enough said.

 

I sis a slp loudmouth 1 on mine and it was loud on a stock lt1. Your will prob be waaaaay loud.

 

I'm curious about what kind of power you have, the car I'm changing the exhaust has a LME 408 with TFS 220 as cast heads wit a 253/259 643/612 112 cam, has a 6 speed but I'm converting it to a TH400.