Hey all, just picked up a 1987 TII Rx-7 with a S4 engine. I am currently in the process or rebuilding, and rust proofing it. The stock exhaust mufflers rusted through, and fell off on my way home . This has me wanting to replace the whole exhaust system. I was thinking the REV TII exhaust system by Racing Beat. Now here is where the questions start.

• What is your guys/gals overall opinion on this system, I do not have to pass emissions testing. Is there other good options that I am looking over?
• I will have to install a fuel defender. I was thinking the Turbo Rx7 HKS Fuel Cut Defencer (4501-RA002). What are your opinions on this unit?
• This exhaust will reduce back pressure, will I have to alter/upgrade the fuel system at all?
• With the drop in back pressure, boost should go up. I am going to port the waste gate. Will this be sufficient, or will I have to add a boost controller?
• I want to keep the boost stock for the time being, what is the stock pressure on the S4 engine?
• Would it be a good idea to remove the ACV? If so, what is the best way?
• Any other comments/concerns that you might have will greatly be appreciated!

Thanks for taking the time to look at this post!

 

the Rb system is a really good trade off, its quiet, it fits, its easy to get, and the price is reasonable. there are some Japanese exhausts, but they end up being expensive and hard to get, and usually louder. you can custom make something too, but it will probably be louder, fit and cost can go either way...

if you're going to keep boost stock, then you don't need the FCD, although getting the boost that low might be tricky

if everything is perfect, the stock fuel system is ok. you should change the fuel filter, and the sock in the tank 952-0043 is the ND part number. it doesn't hurt to check the voltage at the pump either, with the pump unplugged you should see battery voltage - 0.5v, any more than that and you need to start checking things, like the ignition switch. if you had a buddy with an FD pump hanging around, its a nice upgrade.

a boost controller can only raise the boost. i find that the boost control is a balancing act with the S4 turbo. my current car actually doesn't boost enough, target boost is 13psi, and it only hits ~9ish, but when i had a car with only a cat back and HKS filter, it would boost like crazy. balancing the restrictions on the turbo helps a lot.

nobody knows what stock boost is on an S4, nobody has had a running one that was stock! fuel cut is like 7.25psi or something and the wastegate is ~6psi, so somewhere between the two, the S5 runs a little more

when you start to mod the car it is a really good idea to look it all over, and start with new filters and plugs. the JDM tuner way is also to check the function of everything before you put it (back) on the car. if you verify stuff works, these things are a lot longer lived.

 

You want to make sure that if you get the racing beat system, you get the full system or just the catback. The two are not interchangeable, i.e., you can't buy the cat back version and then buy the rest of the system and have it bolt up. I was a little disappointed with my system, the polish isn't what I'd expect on the mufflers. Looks like they finished some sections with a wire brush and forgot to polish it, I ended up hand polishing mine to make it look uniform. You will have to fight with the fitment, the left side muffler will hang lower and have a big gap, so you'll have to modify it a little.

When I put it on my stock S4 it did cause boost creep and hit fuel cut. The gauge only goes to 400mm/Hg (7.73 psi) and it was going past that. Stock boost is only around 6.2-6.5psi. Instead of getting a fuel cut defender (FCD) or some other piggy back system I just welded in a restrictor plate in the exhaust to increase back pressure. This way you don't get boost creep and you don't have to port the waste gate and all that other malarkey. Everything else is stock on my car (original engine too).

I bought my system mainly for looks, so I don't mind if I don't get the claimed power gain (which I doubt you could without other mods).

 

For sure port the waster gate to help control boost.

Wastegate Porting guide for S4
FC3S Pro v2.0: How-To - Zenki wastegate porting

I love my RB exhaust