[trz1000]

On my 72 Jimmy I'm running Hedman 69230 Hedders (Had to dent #4 and #6 primary tubes to clear the frame), 2.5" pipes through Flowmaster 40's to 3" tail pipes side exit behind the rear tires. I haven't run it yet but I've run flowmasters in the past and love them. Some people hate them. I wanted to go with Flowmaster 50's and 2.5" tail pipes but I got such a sweet on the 40's and 3" tails that I couldn't resist. The setup may too loud so I have a set of car chemistry baffles on the shelf to weld in if needed.

I don't recommend 3" pipes as they take up a lot of space and are a pain in the butt to route. The tail pipes were tough enough but I don't know how I would have cleanly cleared the transfer case had the pipes between the hedders and mufflers been 3". I don't have a bender so I make my bends by cutting and welding elbows to get the right angles. Takes a long time. I probably have 10 hours in fab-ing and installing my exhaust system.

Another side note I read an article some time ago that said going from 2.5" to 3" with the same mufflers will increase the maximum volume by 10db. I believe it though I don't have any official numbers to prove it. I ran a 68 Galaxie with a 2.5" H pipe system and a 3" X pipe system through Flowmaster 50's and the 2.5" was nice and loud but civilized. The 3" system hurt my chest when standing behind it at idle. It was awesome. Had to shut it down to order at the drive through.

The P.O. of my Jimmy had a 2" setup with a side exit in front of the rear tires. I didn't like it too much as the pipes ran between the spring and the frame. Also the tail pipes were real close to the tires, like a couple of inches. I think if you took your time designing it, you could make it work and look cool. P.O. had some cheapie hedders and some generic turbo mufflers. Sound was too tame for my taste.

Another option if you want to exit before the rear tires; I had an 87 Dodge pickup in school that I ran 2.25" pipes off the manifolds through Cherry Bombs that were mounted right under the doors. Exit was just past the cab corner. Hey, it was the best I could to to make me some lake pipes while on a college kid budget. Nevertheless I thought it sounded awesome; tough but not annoying at all.

FWIW My 71 long box has 2.25" from manifolds through some generic turbos side exit after the rear tires. Sounds good but I like the Flowmaster sound better. I think the turbos are Thrush.