I used to know a guy who used a O2 simulator, it was a hard wired simulator though, you plug the rear O2 bungs and then wire this "box" to the O2 wires and bolt it to the frame and it simulated the heating and workings of the O2's, but it was expensive, like $100 and you needed one per side.

 

I have my exhaust running straight through to one flowmaster super 40, it sounds great. Its a little loud but I like it that way. My CEL stays on due to my O2 sensor that is not installed correctly, it is offset by a brass bushing that I had to install to correct for the wrong size O2 bung, but I still manage 12 mpg with a lift,bigger tires and my heavy bumpers. I noticed that I do have better throttle response too. I'm not worried about burnt exhaust valves because of the poor design of rover heads, its bound to happen anyways.

I say go for it, it won't hurt anything. I also live in SC in the upstate, no emissions testing is great sometimes.

 

Are you wanting to do this for performance benefit or mainly for sound? I dont really see that making a performance difference, it may even hurt you a bit in that dept. Sounding more powerful and actually gaining power where it's needed are totally opposite. Freeing up the exhaust often nets a bit of power but you have to do it in the proper manner otherwise it can do more harm than good.

You could keep the cats, ditch the "y" and run a true dual system with side exits. That merge combined with the factory tubing, muffler and resonater chokes up everything. Upgrading to 2.5" or 3" tubing after the cats with a decent set of mufflers wont cost much and you'll might get a little bump in performance not to mention a good sounding exhaust. Wouldnt cost a whole lot if you can do it yourself and it sure would be better than having the CEL glowing and possibly causing damage just to annoy other drivers. Also beats paying $200 to trick the ECU with simulators and you may actually benefit more than noise from doing it my way. If you like spending money you could even throw on high flow cats.

 

As stated before you have to remember these aren't blown motors so they do need some back pressure for optimal performance. There's a state of not enough and a state of too much..

 

From a physics point of view, I'm trying to get my head wapped around this "less pressure equals more heat" thing (burning exhaust valves)... In the normal world more pressure yields more heat, while less pressure yields a heat reduction...

Running less "back pressure" used to be a big issue with 2 stroke engines because it effected the intake portion of the stroke... But, with 4 strokes other than the very short overlap at the end of the exhaust stroke, the intake and exhaust are separate and isolated from each other... I would think if one were to get the engine management computor happy (the O2 sensor issue) that running straight exhaust would be an advantage... But then again, maybe all those dirt trackers and monster truck folks have no clue of what they are doing (headers only)...

 

It really depends on the application, high displacement/high horsepower engines often like open exhaust. A blown injected 526 Hemi (common in Monster trucks) is a different beast than a bone stock pig of a 4.0 v8 that we have in our Rovers. The only thing those engines have in common is that they are engines. Those race specific powerplants flow so much that exhaust often just kills them hence the open headers. These Rover engines (and most small displacement engines) need backpressure to perform efficiently and also to make torque and hp, lose the mufflers you lose their scavenging ability. The exhaust valve thing is old science and can be debated, what cant though is the almost certainty that straight pipes on this type of motor will probably kill it power wise and cause it to run like poop.

 

I'd do a pipe with a slight curve in it...

 

you can be certain that it will.

besides robbing you of power, being obnoxiously loud, and lighting up the CEL... there isnt much this will accomplish.

 

It would certainly simplify the setup. I've read so many conflicting articles about back pressure I don't know what to think anymore.

 

ill qualify what i said earlier by adding that you can count on not making anymore power without any modifications to the ECU.
whether it "feels" faster afterward, it wont be.

one could also argue that there would be little to gain even if you could "tune" the ECU afterward, but thats beside the point....