Im thinking installing some 7 inch stacks. My questions are how loud will they be in the cab if they are cut off so they dont stick above the cab? Second question is living in South Dakota we get all types of weather do stacks need to be covered? Third question is what is the best way to build a system, with the y pipe in the bed, or under, and is flex tubing enough to allow for the bed to shift? Thanks

 

they will be loud i cut mine so they stick above the cab about 2in the higher you go the less noise you get. flex pipe will be fine, i ran mine in the bed the fuel tank is impossible to get around unless you are using 4in or smaller pipe. i dont cover my stacks but they do get the truck dirty when it rains enterprise engine sells stack covers if your worried about it. why are you going so big even the pullers dont use that big of pipe

 

The reason that im going with 7 inch is because i can get the pipe for next to nothing off an old recked truck. I will go with 4 inch from the turbo to the y pipe. Has anyone ever used a box to go from 4 to 7 inch. Im probably going to have a hard time finding those kinds of reducers.

 

If you are gonna use the 7inch stacks, I am not to sure what you are using for a box, but on mine I am using a 4x4 square tubing alot of guys use 6x3 but whatever, at the ends of the tube just weld a piece of flat steelon the top side of the tube that is like 7 1/4x71/4 and cut some 4 or 5 inch holes into the plate and tubeing that way you can weld your pipes right to the plates or cut of about4 inches of each stack off-,slit them down a little and weld them on the plate, then slide your stacks over them and clamp them, then just cut a 4 inch hole on the bottom to run your 4 inch pipe into itfrom your existing exhaust On mine, I cut a square hole just above where my 4 inch comes up from the bottom of the tube and welded a piece of angle iron upside down ,to V-the smoke I also slanted the ends of tubing to push the flow up through the 2- 4 inch pipes that I got coming out my holes about 15 inches long then I put my 5'' stacks over them,this keeps the rain out a little better, I think-just my opinion....... hoping to put them in this week! anymore Qs dont be afraid to ask......

 

they make 5-7 adapters, so you'll be fine there...

but I'm gonna guarantee you right now that those things are gonna be LOUD... they're gonna resonate like CRAZY... if you've got a single cab and ever want to roll the windows down, I would invest in some ear plugs.

I had 5" slash cuts on my single cab about 10" over the cab... with the windows down it was rediculous... don't get me wrong, sounded awesome, but it was LOUD...

I put a pair of curved tops on it facing back... didn't really help the resonance w/ the windows up, but made all the difference in the world w/ the windows down... still really loud, but not painfully so. and as an added bonus, it's louder outside the truck than it was w/ all the sound waves going straight up

also, don't take this the wrong way, but I think 7" stacks would look rediculous on a CTD... they look great on a big truck, but I'm not a fan of huge stacks on a little pickup... especially the miter cuts... it looks like you're hauling around a couple tall barrels in the bed or something.

oh, and unless you're planning on making 600-700hp down the road, I'd go w/ the box crossover... MUCH easier getting everything all squared up. I did 5" Y in the bed... it was a real beating getting everything squared up right. didn't help that I was flying solo and didn't have anyone to hold while I tacked.

Forrest

 

I saw a older power stroke at a pull a couple years ago that had 7" stacks, miters, looked pretty cool i thought. He just needed some smoke to fill those pipes

 

These are real loud:

https://www.dieseltruckresource.com/...cat/525/page/2


And these are even louder:

https://www.dieseltruckresource.com/...cat/525/page/3

The first one is mine and the second one is my sons. I would think sevens would be unbearable.