Dual exhaust advice

jdell · February 2, 2012

Any body have any input on this system?

Flowmaster 817492 Cat-Back System 409S Dual Rear/Side Exit Force II Moderate Sound Exhaust Kit. Amazon.com has this for sale at $443.99.

Is this a good kit worth doing? How is the sound? Noisy?

Thanks guys.

Stevens03 · February 2, 2012

Personally I'd stay away from Flowmaster. I had it and although the sound was awesome, it rusted out in just under 2-1/2 years with Pa. Winters. I also lost low end torque and mileage with that kit (03 5.3L) When it rusted out, I replaced it with Magnaflow. It's full stainless steel and uses SS. bands instead of clamps. It sounded awesome and I pickedup the mileage and low end torque I lost with FM. Also very similar pricing for a full stainless system that feasibly could be your last.

jdell · February 2, 2012

Thanks. I am located in NJ so our winters are about the same. You made up my mind for me, I will start looking for a Magnaflow.

jfjohnson · February 3, 2012

I am replacing the entire exhaust system on my 99 Suburban this weekend. I am installing MagnaFlow Cat system, all stainless steel from the exhaust manifolds past the catalytic converters then into a 3" pipe to a FlowMaster 50 Series muffler. Continuing the 3" pipe out of the muffler all the way out the back of the Suburban. Anybody had any issues with a single 3" pipe? I have read on a couple of forums not to use dual 3" pipes because there was not enough exhaust flow and this would decrease low end torque and power but it did improve the higher RPM performance.

Any information would help.

Jeff

BlackZ71Silverado · February 3, 2012

If I were you I would look at a good quality stainless system. The Flowmaster will not last very long in harsh climates, they are know for rotting out. Borla, Corsa, MBRP, Magnaflow would all be good choices IMO.

jfjohnson · February 3, 2012

I might at a later date but right now I am not setup for good stainless welding, I need to get it back on the road. If it lasts 5 years I will be happy. I live just south of the Red River in Texas so our winters aren't bad we just have really hot and dry summers. And this vehicle has 325K miles and isn't a performance ride, just a daily driver and occasional hunting rig.

Thanks for the information.

Jeff

BlackZ71Silverado · February 3, 2012

You don't NEED to weld the system.

jblakeney · February 3, 2012

Why weld it? Just use clamps. .. ... I see a lot of people, burn in the joints but, to each his own. If it was mine I would use a clamp or butt weld the pipes together.

What's the point in the slip fitting if your just going to weld it?

Oh yeah, I don't remember which flow master system I had but, it lasted about 8 years down in south Mississippi and it rusted out. I replaced it with a borla system. I think the system I had was 17257 it was a force II system and it was quite. Unless you got a little load on the truck.

Jbo

jfjohnson · February 3, 2012

I'm welding the pipes together because they will butt joints not slip ons. The MagnaFlow section is slip together and that will be clamped not welded. However, the section right after the cats, where the two pipes meet at the flange, the other side needs to be fabricated into a single 3" pipe, that will all need to be welded. The 3" pipe going to the muffler will be welded to the muffler and so will the one coming out the back. I've had some bad experiences with clamping systems together and decided to weld it this time.

Jeff

Doug_Scott · February 4, 2012

Stainless pipes sometimes will not be able to get the clamp tight enough. Back in the late 70's my buddy had little Fiat. He got the full stainless system from one of the old day speed shops (Piranha). System was made by Borla. If we used the clamps, they would not crush the pipes to make it tight. Even tried heating the pipe near red hot, clamps just would not tighten enough.

We ended up slipping the system together, with all the males ends covered in RTV, and at each connection we drilled and used pop rivets. This exhaust was finished with that black crinkle finish. The male end of the pipe did not have the crinkle finish. Never had an issue with that car's exhaust after that.