20HP? upgrading your catback isn't going to give you 20HP. The best way to upgrade your exhaust and maximize your output is to get a new header *Racing Beat or whatever, then go to a straight pipe out. So basically your exhaust setup is 2 to 2. Each 'cylinder' will have its own exhaust pretty much if I remember correctly. This will give you approximately 25 HP increase if I got my figures right. If you allow minimal backpressure going back to the engine like a 2 to 2 setup, you'll increase HP but decrease your low end power. So your car won't pull as hard during lower RPM, but for higher RPM's, you'll feel a big increase. This is my setup:

Racing Beat headers + Presilencer 2 to 1 to 2
HKS CatBack

I found that this gave good power on all RPM's and also is not too loud as I absolutely HATE loud exhaust notes. Oh, one thing to remember; if you decide to go without a cat, you will NOT pass emissions so this is important if you'll need to bring the car back to emissions eventually.

Good luck!
Peace,
AJ ^_^

 

Nah, if you add the intake you're not going to need to change a chip or anything. What chips do is actually remap everything on the car in terms of the fuel ratio and stuff like that. If anything, once you start getting more and more mods on the car, you'll have to get new fuel 'stuff' like a pump, injectors etc..

Peace,
AJ ^_^

 

If you have to pass emissions then here is what you should do:

1. Upgrade the cats with a Bonez downpipe/high flow cat (single cat system) from RX-7.com.

2. Replace cat-back exhaust system with a quality aftermarket system. The Racing Beat system is my favorite, but another good system that a lot of people go with is the Apex N1. It is available as a single or dual system, but will save you money as a single system. click on the RX-7 store above, or go to www.rx7.com


If you dont have to pass emmisions, then you could get a header and presilencer from Racingbeat. Don't just get the header, cause it won't bolt to the stock cat and if you just use a straight pipe, then you don't have the backpressure required to operate the 6 port induction system which would be a 15% loss in power. Header and presilencer available from www.mazdatrix.com and then follow up with a good cat-back.


Or if you have a fair amount of money to spend and you don't have to worry about emmisions, go to www.mazdatrix.com and go to their racing section and get their true dual complete system. This system gives you a tested 28% (40hp at the flywheel) increase in horsepower on a bone stock RX-7. This is the best system there is for N/A RX-7s.

 

One more thing, you need to have at least one cat converter or a good presilencer with an accomodation for the split air pipe to maintain the proper backpressure to accomodate for the 6-port actuation. Someone might recommend that you gut your cats, but if you gut all your cats, then the 6-port actuation will no longer work. And again, that means a 15% loss of power which defeats the purpose of gutting the cats. If you are going to gut your cats, only gut the two pre-cats. By the way, the 6 port induction is a system which opens two additional ports in the engine to give it better high RPM power without sacrificing low end torque. It operates above 3800 RPM.

 

To keep your 6 ports opening I'd highly recommend either getting the Racing Beat Header + Presilencer, or the Bonez Kit with the high flow cat. Gutting your cat is only for those that have 4 port engines. Anyways, back to your question. ^_- The headers were 190USD and the presilencer ran about the same and installation was a breeze except for moving the dang air flow meter out of the way. I'd highly recommend you bring it to someplace that has a lift and hopefully the owner or whatnot will let you work on it for a few hours. ^_-

Peace,
AJ ^_^

 

I have my 2 pre-cats gutted. My main cat is a High-flow unit from CATCO. My 6 ports still open up nicely.

 

If you have a straight through system, with your cats gutted and all, then I'm not sure if you'll have enough backpressure to initiate your 5th and 6th ports. I'm not really sure. *shrugs

Peace,
AJ ^_^

 

2-1-2? What are these numbers? I saw something along those lines mentioned at the hondachat.com forums as well. I figure it's the way the muffler pipes are split or something (yes, I'm a complete newbie in the vehicular area... but if you need your PC fixed...).

Also, what's with emissions? Are most of the tricked out cars setup to the point where they won't pass the test anymore?

Thanks.

 

The numbers... ok, basically they go like this: Your exhaust manifold has 'holes' that go out from the cylinders and the number of cylinders or chambers is the first number so on a rotary engine since there's TWO chambers *front and rear rotary chamber, it's a 2. Then, the second number is when the header either goes straight through where then there would be another TWO cuz the header's not joining to one *like a Y-piep but on my setup, it's a ONE because it DOES join up. so now it's 2-1. Finally, the last number is the catback. If the catback is like mine where it splits up again via a Y-pipe to TWO cans sticking out the back then you'd get another TWO. So that's it, 2*chambers - 1*headers configuration - 2*catback exhaust system. Hope this helps! ^_^

As for the emissions. Modding out your care to a certain extent won't make you not pass emissions. The real danger from modding when it comes to emissions is your exhaust system. Your catalytic converter is there for a reason. It filteres out the 'bad' exhaust so the crap coming out the rear end of your car is at least managable. In any case, when you gut out your cat *remove the filtering mechanism, you no longer have the filter which takes out the 'bad' exhaust so you'll most likely NOT pass emissions. However, when you gut out your cat, you're allowing the air to flow through freely so there's no more backup so to speak. So if you can imagine water trying to get through a hole in the wall. If the hole is small, it'll filter out the gunk in the water but the water will only flow out at a certain rate. But if the hole is larger, the water will flow through VERY fast but then again, the gunk in the water is also flowing through WITH it. Hope I cleared up some stuff with my explaination and not just confused you some more. ^_-

Peace,
AJ ^_^