Cat back exhaust
 

I'm looking at picking up a cat back this summer since it doesn't cost me any prep points for auto X.

First of all can a good cat-back make a noticable difference on an N/A s4?

Secondly, what are some good catback setups?

Most cat backs give you roughly 5-8 hp and for some good set ups that ive heard of is Borla catback exhaust with a Racing Beat header.

Catback wont gain you much. Why not go with a full RB system?

Not likely. I doubt if you will even feel the difference with just a catback on an NA, maybe 2-3 HP. I would think maybe 15HP if he went full exhaust. The biggest gain is by removing the cats and going with one hi-flow or pre-silencer. I know I felt a big difference in power when I went with the Racing Beat full exhaust.

you can lose alot of weight, and make it sound better at least
i had a catback made at a muffler shop for 100$ and found a header for 160. i'd estimate at least a 10hp gain

If he is trying to stay in stock class, SCCA rules state, "... Any part of the exhaust system beyond (downstream from) the header/manifold or catalytic converter, if so equipped, can be substituted..."
STS2 or SP would allow the whole exhaust to be replaced though.

If I were you i'd first get a header that will give you more hp gains then a catback alone would IMO.

because the price for just the catback setup alone IMO is too much

Ill agree its high. But for the quality of the material and build, along with hp gains and sound, it makes it worth it to ME. I have a RB True Duel on my FB and will never go with any other system on future fb's, unless I go really high hp, then ill go custom 3''

A full exhaust will bump me out of stock class (which i don't want to do at this moment), JUST a cat back is acceptable to stay in stock, and doesn't cost me ANY prep points; where max stock points is 2.

I guess anther question is, if i buy a catback, how easy/hard is it to eventually convert to full exhasut (header back) withc having to get rid of the catback?

...and how much $$$ am i looking at for a (borla? RB?) catback?

On my FC3C S4 I started out by adding a SS Autochrome / Motoria dual cat-back I picked up on eBay for a song. Unfortunately I don't see them selling on eBay right now, but this is a nice set of pipes, "Beat" styled...

http://www.ssautochrome.com/level.itml/icOid/1482

http://www.ssautochrome.com/products/1685.jpg

Later I added the RB downpipe and Random Technology cat, (this drops the two pre-cats, and the RT cat alledgedly flows like a presilencer, but will still pass emissions, other than visual of course...)

The cat-back alone power increase seems quite minimal, but the aesthetics of look and sound are not to be underestimated. Adding a cat back now shouldn't limit your options later for headers, downpipes and such as they're often designed as bolt-in replacements matching the mfr. fittings and sizes, and custom exhaust work is really no big deal if you want to do something different.

Let me clarifying by adding, unless you decide to go true dual exhaust.

N/A Racing Beat catback exhaust:

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

N/A Borla Catback exhaust:

http://www.borla.com/applications/lo..._System/14192/



Personally id go with the Racing Beat.

I got the racingbeat catback, and i didn't notice any gains whatsoever (other than looks) untill i got the downpipe and presilencer.

Are the RB catbacks only available online?

A slightly off topic question...are the aux ports activated by the air pump, or exhaust back-pressure? Cause in my Haynes manual it looks as though they activate from the air pump, but the RB header has a aux port pick-up tube.

S4 aux ports open through exhaust back pressure. S5 open by the air pump.

I got my Borla catback lightly used from a guy on here for $400 shipped. I've seen racing beat catback systems go for a couple hundred used, but those were in slightly rough shape.

I'd suggest posting a "WTB" thread in the for-sale/wanted part section.

I wound up starting w/ a RB Header & pre-silencer, leaving the stock y-pipe & mufflers. That melted the mufflers within about a month.

I mulled over going RB or Borla catback, but ultimately went w/ Borla for a more stock'ish tone... I'm VERY happy, but am hardly a dyno god... Just a guy who wants a sweet street 7.

Do you really think the Borla cat-back sounds more stock-ish than the RB? I'd always heard the RB was very quiet. I had the Borla on my mildly street ported '90 GTU along with the Bonez cat, then later used a Random Technology cat with a stainless downpipe I got made at a muffler shop. Always kept the stock header. None of these combinations was quiet. With either cat, I had a bit of a drone at 3100 RPM, plus the overall sound was pretty loud. I got used to it, but my wife more or less refused to ride in the car!

MmSadda, Do you really think the Borla cat-back sounds more stock-ish than the RB? I'd always heard the RB was very quiet. I had the Borla on my mildly street ported '90 GTU along with the Bonez cat, then later used a Random Technology cat with a stainless downpipe I got made at a muffler shop. Always kept the stock header. None of these combinations was quiet. With either cat, I had a bit of a drone at 3100 RPM, plus the overall sound was pretty loud. I got used to it, but my wife more or less refused to ride in the car!

McHack, Do you really think the Borla cat-back sounds more stock-ish than the RB? I'd always heard the RB was very quiet. I had the Borla on my mildly street ported '90 GTU along with the Bonez cat, then later used a Random Technology cat with a stainless downpipe I got made at a muffler shop. Always kept the stock header. None of these combinations was quiet. With either cat, I had a bit of a drone at 3100 RPM, plus the overall sound was pretty loud. I got used to it, but my wife more or less refused to ride in the car!

I can't say for certain, I dont have exposure to the RB's tone other than in videos. IMHO, the RB header + presilencer + Borla Catback is hardly what I would consider "loud"... To me, It has a nice deep full sounding tone, & not pingy. Again, YMMV & IME...

You know what I would like to hear, a racing beat header to racing beat pre-silencer to borla catback. Then we can compare the sound to my full racing beat exhaust. It does sound kind of pingy like you said, my N1 was a lot deeper then the RB catback all the way through the power band. If I could have the looks of my RB catback with the deep sound of the N1 just quiter I would be golden.

Here's my racing beat full exhaust: http://sdjones.org/exhaust/rb_collected_no_load.mp3

Hate to be the one to say it. But if your trying to stay in the stock class. Seeing as a catback will gain you little to no horsepower. Is there anything else you havent done that you can do and still remain in the class? A catback will run you $500-$600, vs. doing other mods now and probably gain more hp, then go full exhaust later for only $200 more...