I have bad cats in my '89 vert and was looking at Racing Beat's replacement downpipe and presilencer .... my y pipe and mufflers are OK

any recommendations on going this route instead of their header and pre-silencer ? ..... emmision testing won't be a problem

 

well unless you have a turbo, you need the header

 

Sorry, but that is wrong.
Racing Beat offers what they call a downpipe for the NA as well. It funtions exactly as same as the turbo downpipe - it connects to the stock exhaust outlet (exhaust manifold on the NA models, turbo on the turbo models.) So with the downpipe you keep the exhaust manifold, while the header replaces all of it.
Personally, if you have the money, I would just get the header. The only advantage of the dp over the header is that it is cheaper. The header will probably end up being a little louder, but it will also probably get a little more power. And if you end up porting your engine in the future, it will definately yeild more power.

 

yea , this was the link for downpipe specific for the 89 NA

http://www.racingbeat.com/FRmazda2.htm

they still claim some reasonable hp increase with this . if it was close enough to the header in hp it might be alright for me . If the engine goes , i'd likely do a TII swap not porting . Hard to describe how much louder the header/silencer is than the downpipe/silencer i guess?

 

uuuummmmmmm.......it gets pretty damn loud i got the full header with a bonez hi flow cat and corksport cat back- and if your replacing the manifold and cats, you should think about upgrading the cat back too- just do the entire system- thats what i did. But its up to you just a thought

 

yeah you can use magnaflows $59 2 1/4" cat with Racing Beats downpipe/semi-headers, and it will pass with flying colors. Just get 2 extra flanges so an exhaust shop can weld that cat to them, and then it will just easily bolt together (vs welded permanently).

 

with stock ports and stock intake and stock ECU there is no advantage at all using a header instead of a down pipe on a non turbo. Power is almost the same (only a couple HP difference).

But there are several draw backs to a header over a down pipe:

#1 noise... header is considerably louder
#2 cost... headers are generally at least 50% more than a down pipe
#3 longevity... headers don't hold up as long as a down pipe and stock exhaust manifold.

The exception to this is when using true duals (a single exhaust all the way back not joined at any point, for each rotor). When using a true dual, there is a noticeable gain in power over a collected header or a down pipe.

 

I am not ready to go true Duals on the vert .... don't really care about maxing the HP potential at this point and a little lower noise compromise is OK with me

if i go downpipe/silencer ... any other changes needed for it to run right or just bolt and go ?

 

just bolt up and go

 

for all the help.

i'm going to go downpipe / silencer, when the Y and mufflers go, i'll just add the rest of the RB system to the back

 

Just installed new Corksport header last night.... Definetly added noise... pretty tinney sounding, but i am running a HKS style 2.5" cat back as well.... wondering what it would sound like on stock exhaust..OR... any ideas on getting a bit of a deeper rumble? not so much a .... "hey im a civic driving douche!"............????

 

As far as headers not having an advantage over a downpipe on a stock engine, as a person who's owned both I'm going to have to disagree. It's not even a comparison. A header gives tons more usable power. If all you look at is a dyno chart, you'll see a little bit of a gain. Too bad a dyno chart doesn't tell you much useful information. It only shows full throttle. What about the other 99% of your powerband? A dyno does not show how a car behaves at part throttle unless you test it there but who does a part throttle dyno run and then posts it for comparison reasons? Nobody does. It's true that a header will be much louder. It's not necessarily true that it will fail before a downpipe does. No one has any evidence to support that and claim it as a fact.

It is also a bogus claim that a true dual is a noticable gain over a collected system. That needs to be quantified by connecting it with a certain scenario. On engines like bridgeports and peripheral ports, you absolutely must collect it to get the most power out of the engine. A true dual will always make less power than a collected on these engines. On less agressive porting such as stock and streetports it really depends on what you want from your engine. Where you collect a header makes a huge difference on power output. A long primary system gives fantastic benefits in power over the whole rpm and load range compared to other systems. A true dual does have it's advantages. They sound very unique and many don't like the tone. Some do though. It's all a personal preference. I don't like it but that's me. The closer to the engine you collect an exhaust, the higher pitched the tone will be. The larger the muffler you use, the less raspy it will be.

The stock mufflers do not sound very good through a header. A straight through muffler is also not a very good way of quieting one down and will typically be raspy sounding. Fortunately you do not need a straight through muffler to get all of your power although many people falsely claim otherwise. Which muffler flows more compared to the other is irrelevant as long as they both flow what the engine needs. A simple Dynomax superturbo muffler can be made to work very well with a rotary. Yes they are fiberglass and no they don't just burn out. I've never killed one. They muffle well, flow at least what the engine needs (that's all that's important), and have a good deep not raspy tone. They're cheap too.

 

I pretty much agree with rotarygod on this one. For one, I've never heard of headers failing, espeically the RB ones. I'm not saying it doesn't happen, just that I've never heard of it. I also noticed better overall power from my header vs the downpipe. I can't say much for peak power, but it definately felt better in city driving. Yes it will be crazy loud with a corksport, but so will the downpipe. I really didn't notice a whole lot of difference between the two. He also mentioned a y-pipe, which means he doesn't have a corksport exhaust, so its irrelevent for this discussion. Also, my friend had dynomax mufflers with the RB dp/presilencer on his car, and they sounded great. I have no experience with true duals, so I can't comment on them.
That said, if you are planning on swapping in a turbo when the motor goes and not port it and keep it NA, then the downpipe is probably your best bet. It'll save you some money and still have good power.

 

I used the RB header pre-silencer combo with the stock mufflers for awhile and I didn't think it was too loud. Don't know if it was much if any louder than the HKS. The big difference is that above 4000rpm the stock mufflers sounded like an RM80 dirtbike or some other small two-stoke. I've never heard the downpipe through the stock mufflers so I can't comment on it.

 

If you keep your RPM's low and your timing adjusted right, it will not be loud.

 

Where's the fun in that?

 

i generally keep the vert between 4000 and 6000 , with occasionally trips to 7K, whether on the highway or city. I love the tone from the drivers seat of the stock system with cats.

I hope the RB downpipe / presilencer I'm leaning towards will also sound good at that rpm range and still allow the car to be seen before it is heard .......... the harley and fart can honda exhausts don't do it for me ...... I also still like to enjoy CD's and the headrest speakers with the top down, but i don't mind turning up the volume

 

u have a pm!

 

Not too often I disagree with almost everything you say in a post. I guess my experience with mutiple non turbo FCs since '87 must be quite different than yours.

 

I think this was covered awhile ago during another sparfest regarding collected vs. true dual.

I think it was agreed upon that true dual was the best for stock port engines and mild streetports. However, the collected header shines once the porting becomes more aggressive, like aggressive street, HBP, BP, JBP or PP.

Not to threadjack (well, maybe), but whatever happened to people running J-Bridges? You really don't hear of them anymore.

 

Sorry to dig this up, I must have missed these last posts. Anyway, I just wanted to say that my engine has an agressive streetport, which is probably why I saw as much difference as I did.

 

should I be prepard for any bad smells with the Cats off ???

or am I just generally adding a few more odorless greenhouse gases and particulates to our air ........ global warming for us living in winnipeg may not be such a bad thing

 

yes (or at least i did). It will smell really rich, and if the parts are new you will get this weird smell from the packing burning up and breaking in (only for a week or so).


i went with the RB downpipe + Presilencer + Y Pipe + mufflers and i love it

it's a real mellow tone in the low RPMs and once you step on it the tone becomes more aggressive, but not ridiculously loud... and it backfires!

keep in mind my car is completely stock other than the exhaust and intake.

 

I'm just going off of experience since I've tried all 3 systems on both ported and non ported engines. I've even tried different collector sizes and find anything larger than a 2.5" pipe to be completely worthless on a street engine.

 

yep, same here. See that I agree with.

All my 18+ years of FC exhaust testing and experiece with everything from RB headers, to custom exhausts from the block back, make me dis-agree with your earlier post.

Of course, That is on Non turbos. And in 50% of the cases on different FCs that must meet at least the sniffer for emissions testing. Turbos are a whole different ball of wax and I have not played with exhausts at all on Turbos.