What would be the noticable difference between the two? Is one better than the other?

You might get a little deeper tone with the 5", plus it looks a lot better. As far as performance, not really any improvement. You're already gonna get enough airflow with the 4" that I wouldn't think there would be any noticable drop in EGT with a 5". If guys with like 700 hp trucks run 4" I think thats good enough for most of us. But don't get me wrong, the 5" look sick, and I actually kinda wish I went with a 5 inch system.

Are you getting any codes since you went with the exhaust and dont have the finger stick yet? My muffler is gone, but its still quiet. I need a little noise.

I do not get any codes no. I've heard that's kind of luck of the draw though. Even if you do its a soft code it won't limp it or anything, so I wouldnt worry about it. And yeah, taking the cat off will definitely give you some serious noise.

im having the same problem myself XDP has an mbrp 5'' for cheap same with the 4''

I just installed my 5''mbrp turbo back 2 weeks ago, I had a 3.5 straight pipe before that. I thought the 5'' would be a EXTREME change but it was not. Dont get me wrong I LOVE IT and Im glad i got a 5'' instead of a 4''. I guess I just need to hear my truck WOT while im driving next to it. A lot of people complain about drone at 60mph-65mph but it does not bother me.

And you can get a 5'' mbrp for $388.00 shipped to your door,

http://www.alligatorperformance.com/

I ordered mine on a saturday and got it on wensday the day before thanksgiving.

When I removed my muffler and cat I did get a engine code on my LBZ but I had already ordered a egr blocker/finger stick for it. Installed the finger stick in about 30 minutes and cleared the CEL with edge and no more CEL since.

There is no noticeable difference between the two except noise. Plenty of fast trucks running 4" exhaust.

I love the look and the sound of the 5" system. Flo Pro makes a stainless 5" that is around the same price as the MBRP aluminized 5"

4" is all you really need, but 5" does look and sound great. Its all personal preference really. Most people with LBZ and LMM trucks like the 5" because it gives a deeper, louder sound. Let me know if theres anything I can help with.

I just put the MBRP 5" on my truck with a 6" tip an think it looks great. My biggest thing is that the 5" didn't fit worth sh*t. Only 2 hangers hooked up the right way. Wasn't happy about that but maybe I got a retarded kit. Sounds good, an is louder than my stacks on the highway but I don't mind that.

I hope you don't mind a lil thread jack.... I'm a lil confused about the down pipes i've seen for sale. I thought a turbo-back exhaust system was exactly that... from the turbo down all the way to the back bumper. But now i'm getting the impression that a turbo-back system is really from the down-pipe back???

yep, from the down pipe back.

I just put the MBRP 5" on my truck with a 6" tip an think it looks great. My biggest thing is that the 5" didn't fit worth sh*t. Only 2 hangers hooked up the right way. Wasn't happy about that but maybe I got a retarded kit. Sounds good, an is louder than my stacks on the highway but I don't mind that.

Most of mine fit allright but I am sure glad I took it to a muffler shop to get it installed because I did run in to some problems. Plus he was gonna put it on for free anyways since I send him so much business.

I dont think all kits are the same no matter what comes from the factory, there is allways some a**hole what cuts a extension pipe to long or short or in my cause welds a hanger on backwards from the factory.:eek: go figure

But as far as the quality and price and shipping/vendor 100% top notch two thumbs up.:D

I have 4" turbo back now but have been debating 5". Mainly bc i am lifting my truck and think the 4" with 5" tip will look to small after its up in the air, so a 5" with a 6" tip would look better. Also think it may change the sound and hopefully the egts some, but idk. What yall think?

I have 4" turbo back now but have been debating 5". Mainly bc i am lifting my truck and think the 4" with 5" tip will look to small after its up in the air, so a 5" with a 6" tip would look better. Also think it may change the sound and hopefully the egts some, but idk. What yall think?

Go with it, you can get a 5'' mbrp turbo back for $388.00 shipped. $80-$110 for a mbrp/RBP tip.

I hope you don't mind a lil thread jack.... I'm a lil confused about the down pipes i've seen for sale. I thought a turbo-back exhaust system was exactly that... from the turbo down all the way to the back bumper. But now i'm getting the impression that a turbo-back system is really from the down-pipe back???

A turbo-back kit installs at the clamp on the turbo eliminating the cat all the way back.

A turbo-back kit installs at the clamp on the turbo eliminating the cat all the way back.

Uhh, most so-called turbo back exhaust systems actually attach to the bottom flange of the down pipe. There are only two companies currently manufacturing an aftermarket downpipe Diamond Eye or MBRP. Both are 3" diameter because there is simply not enough room between the engine and firewall for any bigger tube. I hate to tell you but unless you actually install an aftermarket downpipe you only have a downpipe back exhaust.

Are you getting any codes since you went with the exhaust and dont have the finger stick yet? My muffler is gone, but its still quiet. I need a little noise.


Wait til you cut the cat out it want be quite anymore lol:D

Moved to Exhaust.

Uhh, most so-called turbo back exhaust systems actually attach to the bottom flange of the down pipe. There are only two companies currently manufacturing an aftermarket downpipe Diamond Eye or MBRP. Both are 3" diameter because there is simply not enough room between the engine and firewall for any bigger tube. I hate to tell you but unless you actually install an aftermarket downpipe you only have a downpipe back exhaust.

I gotch ya! I get the down pipe and the front pipe mixed up.

The terminology is very easy to get screwed up on these things, but TheJDMan is spot on.

Uhh, most so-called turbo back exhaust systems actually attach to the bottom flange of the down pipe. There are only two companies currently manufacturing an aftermarket downpipe Diamond Eye or MBRP. Both are 3" diameter because there is simply not enough room between the engine and firewall for any bigger tube. I hate to tell you but unless you actually install an aftermarket downpipe you only have a downpipe back exhaust.

Good point. I just corrected my signature. And I agree with kingcrete that it's a good idea to have it done by professionals. No clamps and the welds are hardly noticeable. The hangers are also welded on at the correct positions. It's a work of art.

I currently have an AFE 4" completely straight exhaust from the down pipe back to a 5" tip. My 06 is lifted 6" on 37" tires and I also think the 5" with a 6" tip would look better. I am looking for a deeper sound also, will the 5" straight exhaust give me a louder,deeper tone?

http://www.youtube.com/watch?v=KX4UDW9gReY