Sorry for the newbie question but I haven't been able to figure out what the big differences are between on-road and off-road exhausts such as the MBRP products. There seems to be a definite divide, where some products are clearly in the "off road" category -- does this mean they're obnoxiously louder, or have more clearance for off-roading, or have left out some important piece that's going to make my JK fail inspection if I install it for street use?

I'm particularly concerned about that last one

Also -- if I install an aftermarket exhaust, do I need to do anything to the JK to compensate for a change in back pressure or air flow? Or will the computer do all that magic for me?

 

I have the mbrp off-road. To be short, it will not fail inspection. It's not overly loud at all and is rather mellow sounding with a nice growl. It is designed to be everything you need outta the box. It's a standard aftermarket system. Off-road means the muffler can is relocated from the back to under the driver door, and is smaller, meaning it's more contained and less likely to get mashed on rocks, and gives you more ground clearance. I'll snap a picture if you like

 

Normally an offroad exhaust system is one that deletes the catalytic converters, making it illegal for use on the street, hence the term "offroad use only". The Borla longtube headers are an example. Lately people have been calling a system that relocates the muffler an offroad system as well, but it's really not offroad use only, so the offroad term in that case would IMHO be a marketing thing.

 

My "off-road" MBRP has actually been more useful to my on the road than off the road so far. Most of the trails I have been on have been hunting roads where things are not extreme enough to worry about hurting the stock exhaust. I was however rear-ended by someone at real slow speed in town and their little neon slid under the back of my JK. If I had the stock exhaust it would have most likely been damaged. As it was there was no damage to my JK (the back of my JK rode up her hood on my towhook) and I just drove off her hood, she said she was sorry, and we parted ways

 

Glad you asked the question I wanted to ask. Now, I'll probably go by the off-road.

 

I just installed a Cool Tech...so far I love it!

 

With an unlimited bs the off road exhausts, do you need to relocate to evap canister or is that only on the 2 doors?

 

"Offroad" Exhaust kits simply relocate the muffler from its stock location to under the vehicle.

 

On an unlimited will the heat from this effect the evap canister?

 

It can yes, but the Unlimiteds have enough room, I would recommend moving it anyway.