Recently, my muffler decided to disconnect from the rest of the exhaust system. This wasn't really a surprise, the welds on the muffler seemed kind of weak and even rattled for a bit at one point.

While it's still attached to my car, they are now completely seperated. Luckily, they are so far seperated (the muffler hangs down below the exhaust pipe.. not dragging on the ground, or even visible from behind the car, but about 4 inches down) so that there is no impedement to the exit of the exhaust. Basically I'm running a straight through exhaust.

I took it in to Mieneke (I figured, hey, all they need to do is touch up the weld for right now, until I can replace the exhaust, no harm done letting them touch my car), who told me that they didn't carry any mufflers that would fit that exhaust pipe, which is 4 inches. Apparently that exhaust system was custom made by the previous owner.

Like any good RX-7 owner, I've decided since I have to replace at least some of it (the muffler), I'll replace all of it. I'd like to get a downpipe/midpipe off of www.rx7store.net. I'll admit I am very ignorant to these cars; I haven't even had a chance to put my car up on a lift and look around. The muffler would connect to the end of the midpipe, correct?

Before anyone mentions it, I am exempt from inspections, so the lack of a cat won't hurt me. The only question regarding that is, will someplace install my exhaust system even though there wouldn't be a cat included, or would they refuse on the grounds that it's not street legal?

Thanks for your help everyone!

 

you may want to do a search. There is a LOAD of stuff on here about where to buy downpipes, midpipes, etc. Also, make sure you know what you need vs. what you want for the exhaust or it can get very pricey. Good luck.

 

Yah, I'm mostly trying to figure out what I need. Does the exhaust go from downpipe, to midpipe, to a cat back? Or straight from the midpipe to the muffler. I am having trouble visualizing the setup/components.

Mostly I'm just asking about that, and also if anyplace will install a non-catalytic converter setup on a street car. Will they refuse to install it?

After I figure those two things out, I will be able to search a lot easier and make my decisions.

Edit: Also, something I just read in another thread leads me to believe my car is possibly becoming damaged due to it not having a muffler on it (lack of backpressure perhaps?)? Is this the case?

 

Running no catalytic converter can lead to "boost creep" in some cases because the stock turbo wastetgate can no longer keep up with the large increase in exhaust flow.

If this is going to be a street car I'd suggest getting a midpipe with a catalytic converter in it. The car will be quieter and the exhaust won't stink.

Yes, it goes, downpipe, midpipe, muffler. Those three will replace all your piping from the turbo outlet back.

 

Like John said, the midpipe will stink, and it will be LOUD. Some people like loud, smelly, and obnoxious. (Most cops don't)

As well, if you have stock turbos, installing a full set of downpipe/midpipe/muffler will cause the wastegate to be overwhelmed, leading to a boost control problem called boost creep. ECU or boost controllers don't solve boost creep - you'd need to port the wastegate in order to safely install a full aftermarket exhaust, and that adds a few hours to the job, maybe more for parts.

IMHO, the midpipe is not a 'why not' mod. I would leave the stock cat instead of installing the midpipe, or if you're really bent on making power, install a high-flow cat (downpipe/high-flow/muffler) and upgrade the boost controller so you can run your boost at 10psi where it needs to be.

The faq covers boost spike and boost creep - I suggest you start your digging there.

Dave

 

 

LOL, his title is Dorito spinner. hahahahahaha

 

So it is possible to run a midpipe without an aftermarket ecu? Just port the wastegate? Would the only downfall to this be if you still get boost creep?

 

Porting the wastegate will fix the boost creep. You can run the stock ECU as long as your boost stays at10psi, and at 10psi with a full exhaust you'll really get creep (higher boost = less severe boost creep)

You'll also need a better boost controller since higher flowing exhausts tend to create boost spikes because the stock ecu's boost control is just too slow.

If you're willing to port the wg yourself and install a manual boost controller, the dp/mp combo is really great bang for the buck. If you're paying for labor it makes very little sense.

Dave