MoldyWheatFeet

Hello everyone, I was just looking for some advice as for what kind of exhaust system I should consider that would best suit my car, I picked the car up pretty cheap last year and rebuilt it, but unfortunately the exhaust it has is destroyed/rusted and will need to be replaced. It is an 87 base model with a street port and an omp delete and is just meant to be a fun weekend car. I would like to remove the catalytic converter but have heard that the s4's aux ports open due to back pressure and I am worried that by putting a new system on without one would cause a huge loss in pressure. So I just wanted advice from other S4 people to see what components your exhaust system is made of (not so much the brand) and if you are happy with them. I live in texas so emissions are not a problem. Any advice or sharing is welcome

Akaviri

iTrader: (1)

I highly recommend Racing Beat. They are super durable, offer a nice gain and the exhaust note is perfect. They are expensive brand new, but it's reasonably easy to find a used system for cheap. I have the 2-to-1 header and catback on my S4 NA - it sounds great and there was a very noticeable difference in power. All used parts, but still great condition, and only cost me around 600 dollars in total.

As far as the back-pressure for the auxiliary ports, even with the tube hooked up like stock, your ports most likely won't come on at the right time. The best method is to hook up an RPM switch and a solenoid with some vacuum tubing from the air pump. Read about it here: https://www.rx7club.com/2nd-generati...itches-907824/

I simply have my stock catalytic converter with a custom extension pipe to mate up properly to my header, and use the stock back-pressure tube. I haven't had time to set up the RPM switch yet as I've been chasing other problems.

MoldyWheatFeet

Thank you very much! what a pain man, if you don't mind me asking is it really noticeable that the aux ports are not operating properly?

Akaviri

iTrader: (1)

From what I've read on here, you lose around 25 hp. It's definitely worth it to hook them up properly.

MoldyWheatFeet

Cool, thats what I figured. thank you very much!

misterstyx69

iTrader: (142)

even if you can't afford the RB system I can tell you from experience that a PaceSetter header will do a decent job for the buck.then it is up to you what kind of setup you want from the header back...dual or single.
If you take and get a tube welded where the 2 runners go to the collector and use that as your Aux port air supply then it will activate them with no problem.

MoldyWheatFeet

Thanks!

j9fd3s

iTrader: (3)

there are two good/easy options for an NA.

quiet street: you keep the stock exhaust manifold. since the manifold flows ok, it actually allows about 90% of the power gains of a more extreme exhaust, but you get to keep the noise down.

so stock manifold into either this Down Pipe / Presilencer Kit for 86-88 RX-7 NT - Manual - Racing Beat or just buy the down pipe separate and then you can put a cat into it if you wanted. the RB parts have the 6 port tube, you keep that, and don't need to think about it.

since this ends up in the stock spot, you can use any cat back you like.

Header style; this one you add the header. RB makes a header, but the way its built means that it doesn't really work as intended, and power isn't much higher vs the stock manifold, but noise goes up. the basic problem with the header is that the engine has 48mm exhaust ports and the header is only 44mm, there is enough meat to fix the header, but they also cheat the bends right at the engine. there are other header options, but its either custom or $$$.

if you're not just buying the RB system, then you next need a good center muffler, and then a good rear muffler to keep it quiet.

ramses666

iTrader: (1)

I bit the bullet & bought the RB true dual system about 15 years ago. It looked way too good to even put on a car honestly... It will Never Wear Out. I removed the little air pipe & made my own port actuation system with RPM switches.

I'm a fan of header wrap, so I wrapped the header & "pre-cat" tubes for a very quiet but Extremely Satisfying Sound. When I get on the throttle the sounds wakes up nicely with no raspiness or metallic noises whatsoever.

Considering that I spent more $money$ for the full RB exhaust system than the cost of my complete & running '88 S4, I'm still Stupidly Grinning with the Incredible Masterpiece the RB True Dual Exhaust.

It's heavy, beautiful Chrome Deliciousness is some sort of sick delight perhaps, but it makes my RX-7 Experience Extremely Pleasureable in Every Way!

MoldyWheatFeet

Thank you all so much for the advice! I should hopefully have this done by the end of summer : )