ilike2eatricers

stats on the car: 91 NA 73k all stock except for soon to be done cold air box with K&N filter

Let me start by stating what I hope to get from the proposed exhaust setup:
1)noticable power gain
2)not unbearably loud
3)able to be smogged (live in CA) or install the cat back on for smog day whenever I need to reasonably easy

I dont feel that all these guidelines are too hard to meet but with loudness and power they in this case may corellate (sp?) with each other.

I am pretty sure I am going with the racing beat catback system but am unsure of what to do from the cat forward.

I see several options for me:
1)leave stock cats on until they burn out
2)gut the precats and install rb streetable header/silencer combo
3)true dual system (how do people with true duals pass smog, I dont believe you can bolt a cat back up since they are uncollected... correct me if I am wrong.

My question is can I get the racing beat
catback system and a streetable header/presilencer
along with the stock cat? I am not sure of the fitment
from the cats forward. I believe there is a small section that must welded onto make up for the portion that is short. My main goal is to be emissions legal with one cat or none OR have a setup where I can keep my stock cat and swap it back in fairly easily on smog day.

Also considering the costs of the rb catback, header
and presilencer it seems to be the equivalent to the
price of the mazdatrix single full exhaust system.

Does anybody know how this compares in power to the
true duals? They dont post any projected numbers or
dyno results for the single system. Santiago seems to think that a cheap collected system will sound worse/louder than uncollected. Does this apply with the mazdatrix single collected system? I dont see this system as very cheap.

I typed this pretty quickly so sorry if you guys get lost or confused... I kept jumbling my thoughts.

Thanks all sorry for the long post. I know some of the requirements and goals of this setup may not be feasible or contradict other goals but give me some feedback. I have been pondering about exhaust systems for weeks now.

1987RX7guy

iTrader: (3)

Well my comments about noise as far as collected and uncollected go are based on my car and MAX-IMAL's car. His FC is considerably louder than mine. I don't know how much better the noise would be with RB mufflers or HKS mufflers but I would say RB is the way to go.

ilike2eatricers

What do you do when its smog time? Or have you not come to that point yet.

mazdized

I have a 89 and I have got the follwing. RB header into 2 1/2 inch RB center muffler, and then HKS cat back. The cat back by itself did nothing, then I had a 2 1/2 inch down pipe connected from stock manifold and the center muffler. Power went up from removing the cats the most, and the sound was almost the same at idle and cruising. Has a rumbling note to it. It started to resonate at 3200 rpm which under load is brain shaking. Finnally has headers put on. not much power gain but sounds way raspier than stock manifold and sigle 2 1/2 down pipe. Dynoed at 143 HP at the wheel.

mazdized

P.S. I think for you the best bet is too leave the stock manifold in that way you can just bolt the cats back on when time comes. I really don't think the gain of noise and $ of a header is worth it for you. I am planning to carb. the motor and later on put in a street port motor with turbo side housing, so I went and put the header on. But for stock motor I really don't think header does much.

ilike2eatricers

thanks for your input mazdized. Is it a misconception then that headers do not give you much power as they are advertised because i was under the assumption that hp and torque increase could be felt somewhat noticably.

Another question for you, when you referred to your single center muffler setup did you do straight pipes right down the middle and the muffler out the center?

Any other feedback/suggestions/input greatly appreciated.

ViRuS

Smog here in the bay is a pain in the @$$. I say get a full street legal exhaust. This way you wont be running around trying to get your cats back on and adjusting stuff. And dont gut your cats, dont throw them away, especially if you get a good (not legal)flowing exhaust cause you will never pass smog. They have the new dyno set up here to, so thats not good news for us. I have no chance in passing smog with my car and it sucks pretty bad...but thats another story.Good luck!!


P.S. Unless You have a hook up on the smog, then it will
not be a concern.

bingoboy

nope. racing beat header will leave about 6 inches or so between the stock cat and the end of the header...or the other end of the cat and the y-pipe...either way the stock cat is too short. taking out the manifold and cats to put in the RB header and presilencer isn't that hard, with liberal usage of a penetrating oil like PB blaster. don't go after exhaust nuts dry, youll break off studs left and right. i think it would be safe to say that a fairly competant person should be able to put them back on in an afternoon for the smogging every other year (*cough cough* don't know what kind of person would do this). with my stock setup the car passed no problem.

can't really say how much power is given to the car with a header only, as i have only used it in conjuction with a presilencer (which eliminated the cat), but with both peices on i felt a healthy pickup in power all throughout the rpm band.

as for cat back exhaust...since i felt a healthy power pickup with the header and presilencer and stock y-pipe and mufflers (that sound like ***) i assume that anything that flows remotely better than the stockers (which i would imagine is just about any aftermarket system) should be fine for a daily driven car. i can't bring myself to drop like 600+ buckaroos on a catback...not sure what i'll end up with yet...we'll see.


that's all i have to add. i have no experience nor know anyone with the true duals so i can offer no opinion.

1987RX7guy

iTrader: (3)

SMOG????

mazdized

I did not quite understand what you meant by straight pipes down the middle and the muffler out the center. Basically what I have is a RB set up with HKS cat back. I have had many different exhaust configurations before on different cars and motors. What I liked the best is a true dual exhaust, but that is heavy, expensive, and non compatible with cats. In my opinion any exhaust needs a center muffler regardless. The only reason my set up is reasonably quiet enough to street is because it is a Y with dual mufflers in the back. If it was a single 2 1/2 inch all the way back it would be too loud for me to steet. (I had the same RB stuff and out to a single 2 1/2 inch piping to a sigle 2 1/4 Super Turbo muffler and it was louder then the HKS straight through. The header I am sure did work a little but like I said I knew it was not going to do much with stock motor, I put it on becuse I am going four port later which will need the header once the motor starts to breath through the Holley 700 CFM carb.

ilike2eatricers

So assuming I leave the stock cat on, what can I do to replace the precats in terms of bolt on or welding on a piping? Does anybody know the length/size of the precats from stock exhaust manifold to the beginning of the main cat?

Spawn VII

YES!!

S - M - O - G ~!!!

SureShot

The biggest power increase from exhaust mods is the header.
Any muffler shop should be able to connect the header to the stock (or high flow) cat.
After that, any free flow cat back will help some more, but the big deal is the header..

1987RX7guy

iTrader: (3)

heh I am aware of what smog testing is. Texas really don't care about smog unless you live in the major sities. Which I don't.

I got my inspection sticker easily. I pulled into the station he said to turn it on. I did. He made my sticker and charged me 20 dolla.

ilike2eatricers

So what would people recommend in conjunction with racing beat mufflers? I am open to other opinions setups that would yield good power but not be unbareable while cruising.

I really want to incorporate a header and remove the precats. If not the header the precats have to go definately.

ViRuS

$20, I wish, not the case here in cali, and I am in a major city. Dyno smog alone is $99.97. (and I can't pass that....shhhhh)Just pray to the Rx7 gods that they dont ask anymore of you cause its bad news if you want more power...but good for the enviroment, nice clean air.

ilike2eatricers

TTT

ThinkGeoffrey

I live in Las Vegas and own a 1990 Convertible 7 that has to pass yearly smog sniffer test but we have no visual equipment inspection.
My set up is RB Header with a Mazdatrix high flow cat to the stock Y and mufflers.
This in conjunction with a K&N cone filter stock air box removed was a huge gain in power and well worth the cost.
The sound is mellow not to loud but enough to make people look and see what is passing them.
I plan on installing a RB cat back this winter but a clutch is needed in first.
Do you have to pass a visual equipment inspection as well as a sniffer?
I know in LA where I moved from they look to see everything is stock under the hood and if not they will fail you even if your car will pass the smog test.

ilike2eatricers

How did you get RB header to fit to the mazdatrix cat? I am assuming you had a piece welded on. Are you referring to the bonez hi flo cat or system?

ThinkGeoffrey

Oh no Mazdatrix makes the high flow cat to fit the RB header check out http://www.mazdatrix.com/e-gray.htm
Every thing you need is there! And I had mine shipped to my house in less than a week they are great to deal with.

ilike2eatricers

cooolios. But dayam 450 for the high flow cat.

I might be considering the bonez race pipe. Does anybody know how this will compare to getting a high flow cat and header?

Here is the link: http://www.rx7.com/cgi-local/2catalog.cgi?cat=4&part=2

If I get the race pipe I can just swap it back out on smog day and this is a much cheaper alternative at $150 to getting a high flow cat and header which would be about 500-700

ThinkGeoffrey

The problem with the bones is you still have the have restrictive stock exhaust manifold and that is where you are loosing the majority of the power not the cats.

If you are looking to go cheep get a pacesetter header it will bolt to the stock cat and remove the Pre cats
It will cost you less than $200.00 and you will get better gains.

But the reality here is speed cost money how fast do you want to go and how long do you want it to last. How much are you willing to spend?

My RB header and high flow cat cost just under $700.00 from Mazdatrix the RB cat back will cost another $600.00 and it is well worth it.
All of my exhaust parts are top of the line parts from the leaders in RX-7 performance it is the only true bolt on HP gain for a N/A so why skimp on the parts.

ilike2eatricers

Yea I know speed costs money. How do you like the sound of the high flo cat and the header?

By the way I would never buy pacesetter ("paceshitter" as they are commonly called.)