I have a few questions about using flex pipe when hooking up a stack in the bed of my truck. I have read historical post for an hour and a half now and gave up on it and thought I'd just make a new thread.

1) Does the flex pipe reduce air flow enough to offset the reason for going with a larger pipe and a stack? Seems the architecture of the pipe would create a lot of turbulance unseen by a smooth bore welded system.

2) Do most have a flex pipe section under the bed so that when the truck torques back and forth the piping doesn't break or bend? I drive large terraces in my pasture day in day out and I'm am worried about hard piping the whole thing becuase I can hear my truck moan and groan when crossing large terraces, straight, angled, whatever.

3) Does anyone have any idea of how much space to leave betweeen the riser and the bedside, or fuel tank in my application? Will the pipe get hot enough to scortch paint or discolor my aluminum diesel tank? I know pulling heavy loads my EGT is 1200F at the manifold, but I have now idea how hot the tip of the pipes actually get 15 feet from the sensor.

These are just a few concerns I have. I would love to put a single stack on the passenger side. I really like the 'bull horn' style.

Sorry for the long post and thanks for any advice. JWB

 

1) I'm running a 18" long piece of flex pipe. I doubt it's causing anywhere near enough turbulence to matter. You could probably run your whole exhaust system out of flex pipe and never notice it.

2)The only reason I have flex pipe on mine is because the pipe coming under the bed was a little above and a little to far back to hook up with the rest of my exhaust.

3) My y-pipe is sitting about 3" or so above my bed and my stacks are sitting about 1/8" off the sides of my beds. My spray in liner hasn't even begun to get discolored and I've been running this system for 2 months now. I won't guarantee that it won't discolor or scortch anything, but I highly doubt that it will. Just because your EGT gauge is at 1200 doesen't mean your exhaust is.

Go for the stacks. I love mine. I get a kick out of em everytime I throw a puff of smoke or fire the truck up. They are a lot of fun.

 

Flex pipe dont flex as well as you might think go with the metal 90* you will spend more time fight the pipe than anything
I have never had a problem with any discoloring of the paint other than black

 

when using such a large pipe on this type of application, the turbulence in a flex pipe is not an issue, you should be worried more about the drive pressure created that the turbine housing.

as for stack heat, i cant see the stack itself getting to more than 200-300 degrees back at the bed. and its only gonna get hot when pulling those heavy loads. i blast around with temps from 1000-1400 on 5x5 with the comp, blowing smoke, lots of heat, driving fast and fooling around with my buddies, and i can get out and touch the stack without burning me...its hot, but its not gonna glow red or ignite anything near it. my cross pipe at the bottom of the bed where it splits was BARELY hot enought to melt a plastic grocery bag that was riding in the bed with some trash in it for about 4-5 days

 

That is good news. Thank ya'll. I have to find the wifey poo a truck before I can work on mine anymore, but that doesn't keep me from planning everything out in advance! I really like the idea of having a one piece, 5 inch, all welded, exhaust put on by my local guy. He is really good. I was just worried about hard mounting the stack to the bed and having hard mounted to the motor and twisting my truck around like I do. Granted it probably isn't that much, but it sure seems like a few inches when I crawl over draws and hills. I was worried about cracking things since the stock pipe is mounted on rubber hangers that absorb and allow the pipes to move as necessary. Maybe it is just the weakness of the overall cab from the famous pillar-less quad cab that make the truck pop and crack.

JWB