I have a 4.0L Rover that is an off-road toy only. It's in pretty bad shape, so not a lot of money is going to get invested here. Anyways, truck started running like crap so I crawled under to investigate and found that the Y-pipe that connects the two manifolds together into a single pipe was smashed almost completely shut. Of course most of the bolts broke off when removing it from the manifolds. Anyways it sounds mean now and I kinda like it! I'm considering just running open exhaust manifolds on it from now on. Anyone got any advice or knowledge related this and the performance changes that go with it?

 

Will prob run pretty lean. Notice some torque loss. Computer should retard enough to prevent pre-det but...

 

I figured the Oxygen sensors would start reporting very lean to the computer and cause it to start dumping gas down the engines throat, which is fine with me. MPG is not an issue for this truck. Am I wrong?

 

Stock manifolds are too short. You're likely to at some point suck some atmosphere back into the engine through the exhaust and cause some real issues.

If it were long tube headers you'd be fine, but for shorties or manifolds you need atleast 18" of exhaust.

 

Besides dumping exhaust into the engine bay and making it hotter, you will be breathing the exhaust in the cabin.

it sounds great but, I promise it will get old quick especially on the trail at low speeds.

if you are dead set on this, I would say drill out the studs, and cut the pipes right after the front o2. This should be far enough to vent the exhaust away from the engine and more importantly away from the cabin air intake