4" is all that's needed

 

 

Appreciate the reply. Thats what I was wondering if 5 inch was more for looks vs performance.

 

Slightly different tone in a 5"

I've stood next to both setups at same time. With no tips
No noticible difference

Ridden in above trucks, 5" was slightly deeper. Not enough for the price difference

 

I went with the 5" hoping not to run into the "hair dryer" noise I hear from most 4" systems. But I have to wait on the UPS man to find out...

 

On a 6.7, a 5" does help with the "hair dryer" sound, IMO.

I've heard a couple 6.7's with 4" straight pipes, and we prefer the sound of mine with a 5".

 

Which 5" did you go with? I've been told that some 5" systems require the removal of the spare tire in order to fit.

 

Flo Pro 5" No Muffler with a Black tip :grin:

 

the larger the pie the deeper your tone i don't really know how w6.7 would sound but goo rule of thumb 4- 440HP 5-500HP if you don't like a big pipe being seen just dump it before the rear axle.Also take into concentration you going to get a exhaust designed for a 6.7

 

I have 5 inch and love it. It is a bit deeper tone than 4" but I think 5" looks better on a big truck (escpacially if it's lifted) or you go with a 6" tip.

 

Yeah I got the 5" exhaust with a 6" tip :grin: Go big! They offered me a 7" but that's just overkill...

 

Yes there is a good 3" of space in between the pipe and spare. There is a lot of adjustment that can be done depending on which kit you got with. With Flo-Pro there is a break on the over axle piece which will allow the tail section to swivel under the truck or stick out past the fender. Also you can twist the whole section where it breaks half way up the main section going towards the motor.

 

Well I got mine on and can say that even with the Flo Pro 5" No Muffler you still get a little hair dryer effect but not nearly as much as a 4". I might order the muffler to have the option and should be cake to put on. The system went on super easy and I did it myself under the truck no lift or jacks! Once it warms up it goes away until you hit the gas a little then you can hear it a little in lower RPM's. BUT that could just be that it's a diesel. This is my first one. Driving it's no louder than my Raptor was in the cab but get on it and it SCREAMS! Did it under a bridge and gave everyone a heart attack...

 

I have the 5" Flo pro and it sounds really good echoing off Prius's that I pass! I had a 4" exhaust and ended up going with the 5" because I liked the deeper rumble. The only time that I wish I had a 4" pipe again is when I am pulling the trailer up hills at 2500+ rpm, it can get a little loud in the cab.

 

how in the hell did you feed a 5" pipe up between the bell housing and hook it to the turbo? if i am not mistaken the turbin outlet is only like 3.5 inches wide?

 

The Flo Pro that I have is a downpipe back system.

 

Which muffler are you going with?

 

I'm going to go with the Flo Pro muffler as it should just replace 1 section of my existing no muffler kit. That way I have the option to run either. The band clamps that the Flo Pro uses are awesome and i have no plans to weld up the kit. It's too serviceable the way it comes and I like that.

 

Yeah, I was happy to see they use band clamps when I ordered mine. Unfortunately, when it showed up, and I started pulling parts out of the box. I noticed that every one of the clamps were bent all to hell from the box being thrown around. I had to take the bolts out of all the clamps, lay them flat on an anvil, and hammer them straight.
Kinda sucked. .

 

Mine were bent but not that bad! 2 of the pipes had to be fixed at the ends though as they were bent up. Had to of taken a good hit for those to bend. They weren't easy to fix...

 

Here's a video you can hear the Flo Pro pretty good in this one. Those that have the no muffler setup like me can confirm that it still doesn't do any justice to how loud this thing is in person. I like it but I keep pissing people off. And now that it's race tuned she blows some smoke on dem prius! HAHA

 

Honestly, if I could, I would go 6"-bigger is better, or I'm compensating for some **** I guess. But in actuality, according to the maths, 4" should be okay for most RPM ranges. I admit that I only calculated the flow for WOT at 28 PSI boost though. The lower RPMs will require a different calculation, as the velocity of the exhaust gas at lower RPMs is much slower. But even if you're putting down 28psi by 1500 RPM, the exhaust size would only need to be ~4.64".

-Source: Going to engineering school

 

I'm running a 5" and love it. Still don't have a tip. What's a good clean stainless steel tip to run? I'm wanting a 6" tip. Any suggestions?

 

I have a 10 in Axle dump 5 inch exhaust and I freaking love it. Axle dump is the way to go for a hidden but clean looking exhaust

 

FWIW I have a 37 13.50 R20 mounted in my spare tire location with a 5" straight pipe exhaust.