MBRP exhaust with Cat back system

[Londell]

Maybe someone can answer this for me. I am looking to upgrade my exhaust to a 4" MBRP cat back exhaust system. I here everyone commenting on how the turbo spools up faster and it sounds cool. But my question is, do you get the same performance and audible effect when you have a cat-back system vs. strait from the turbo? Or do you loose a lot of the sound and performance because you still have somewhat of a restriction still (the Cat)? Also is there a big sound difference between the 4" and the 5" system? Any suggestions or comments please, I plan on doing this upgrade soon.

[Deagon Kennels]

You are not going to gain much power taking your cat off. If you run the cat back system it's not going to sound a lot different than stock. With the cat off I really like the sound. The only time I hear it in the cab is when I get on it. The 5" is going to be a little deeper sound than the 4".

[Londell]

You are not going to gain much power taking your cat off. If you run the cat back system it's not going to sound a lot different than stock. With the cat off I really like the sound. The only time I hear it in the cab is when I get on it. The 5" is going to be a little deeper sound than the 4".
With the cat back system do you still here the turbo spool up?

[More Power]

If you want to hear the turbo, get a more open air intake system. The more open it is, the more you'll hear the turbo...:) The factory air intake system is designed in part to reduce all those noises.

A free-flowing exhaust system can also produce more turbo whine, but it's all behind you as you drive - not alot of difference from inside the cab.

Jim

[Londell]

Hey, thanks alot fellas....I'm placing my order now.

[Londell]

Gonna go with the 5" Cat Back MBRP Alluminized with the 6" tip and the Banks Cold air intake system.

[Freightliner3]

Also think about changing the pinched off driver side exhaust manifold.BD Diesel makes the replacement manifold.You will need to get the exhaust gasket from GM.I changed the manifold.Then added the Banks Ram Air and Banks 4in.Cat Back Monster Exhaust.I took the truck up to the Lake of Woods for some ice fishing and got 20.9mpg on winter fuel, mostly #1 it got down to -20F a couple nights.Thats 7.75% better then I ever got on #2 in the summer,before these modifications.It sounds good and is more efficent also.

[Kennedy]

In my opinion, a cat back system is not worth the money. You will not have near the sound quality (whistle) that you seem to be looking for.

I sell a LOT of front pipes to guys who started off with cat back purchased elsewhere and wanted to upgrade...

Factory air box on the LBZ is also tough to beat.

[FBJR]

In my opinion, a cat back system is not worth the money. You will not have near the sound quality (whistle) that you seem to be looking for.

I sell a LOT of front pipes to guys who started off with cat back purchased elsewhere and wanted to upgrade...

Factory air box on the LBZ is also tough to beat.

I have a 4 in MBRP SS downpipe back exhaust in my LBZ. When you get on it, you can hear it and others hear it to :D

I keep thinking about a CAI and read how good the stocker is, but the air seems warm going in. It read 70-80* today with outside air being around 60 or less. This is via a new Evolution which I like so far very well.

I did round out the sharp inside edge on the intake and put a AFE filter in it. I can notice no diff between it and the stock filter.

My milage was better a few months back, but has gone down lately. I was getting 18 or so with a light foot with mixed driving, now I am getting maybe 16.

I went to LV (600 mi ea way) and averaged 18 going down and less than 13 coming back. I was towing a 20 ft enclosed 2500# trailer under 65 all the way back and was very disapointed in the MPG. This was all with a Diablo 65 HP economy tune. I went to the Evolution for ease of setup and the gauges even though I had a Qudzilla Recon already.

One thing I noticed is the mileage seem to turn down after I did the turbo down pipe. I really don't want the cat back on, but could it really affect the mileage that much?