I know it's unnecessary but I've been thinking about building a 6 or 7 inch straight pipe for my 01 cummins, I'm also wondering what the best sound I can get out of an exhaust? Just looking for ideas and opinions, I like it loud. P.S. I'm not out to make the diesel community look bad, I don't roll coal or run around with my tow mirrors out. I'm just trying to build something a little outside the box

 

Have you measured the gap between the trans and the frame? I think you are going to have a very hard time fitting something that big. Plus 6-7 inch pipe is very unnecessary 4 inch will handle everything up to iirc 800-900hp. anything bigger is a waste. My 4 inch is pretty loud.

 

the 6 inch will barely fit. no way you will fit a 7 inch pipe.

 

Aside from that, you will have virtually NO exhaust velocity, or scavenging and you will lose torque. A 4 inch is plenty, and a 5 inch is plenty if youre running really serious HP numbers with a twin turbo set-up. There's a local fella here in town I met a local car show. He has a a lifted dodge 12 valve CTD. He is running a 6 inch system, from a 4 inch down-pipe, all the way out the back exiting behind the rt rear tire, topped off with a 10 inch chrome tip. That thing is crazy loud, but looks freakin REDICULOUS! I heard alot of negative comments and criticizm about that exhaust system. There is just no point to it!

 

I know of a guy that built a 6" with a 5" downpipe but he had plans for compounds and what-not, I talked to him and the exhaust hasn't caused any problems, no "loss in torque" or anything but he said it's tight..

 

Brother, if your gonna do it anyway, then just do it! When there's a will, there's a way and it dont matter what anyone says. You, ultimately, have to live with it whether good, bad or indifferent. I say GO FOR IT!!!

 

Well said. Its your bed make it how you want to.