Everyone knows the "stock setup" 3 piece catalytic converter system SUCKS... both power & engine life. But the 3 piece design does tend to last a bit longer.

Bonez is the "cat of choice" around this website, but $315 is a bit too much for me. Magnaflow's cheaper CAT alternative
is a 3 piece.... no thanks.

Mazcare (local ATL. rotary shop) is going with an oversized 1 piece Magnaflow on their rotaries now. While not recommended by Magnaflow (warentee reasons), it's got some great advanges:

Upside - near "pre-silencer" flow, HP gains, MUCH better low RPM throttle responce, great sound, keep re-use your cat flanges, passes with flying colors
Downside - 2 years/30K miles max life
Price - $95

Of course this assumes you have full or partial headers which eliminates the pre-cat & middle cat. Those will cost extra if you don't.

So here's some pics and dyno results. Not too bad for a STOCK car with just partial headers, 1 magnaflow cat, stock piping & mufflers, and NO tuning or mods.

Magnaflow 93516





After 2 years, the cat starts coughing up these hairballs:

 

140 hp!

 

Hey that's slightly above stock RWHP on a Bone-stock Series V NA

I couldn't find a Bonez dyno chart anywhere to compare this against.

 

explain to me the "Vert downpipe" The standard coupe setup will not fit?

 

extra bend to clear the Convertible Only front sub-frame. The Vert needs this for chassis strengthening.

 

Ah, thanks. So the bonez High Flow from Rx7.com probably wouldn't bolt right up then. I'll have to call them and see if they have one for the verts. Thanks again!

 

I thought S5 had about 125-130 rwhp stock.
What material would u recomment for the piping? I want to keep my stock exhaust manifold so Im gonna make the local exhaust shop do the piping for me.

 

Keep in mind the local exhaust shop will just WELD it ALL together. If you ever have to get access to the transmission YOU'LL CURSE their cheap-azz welding job instead of being able to "unbolt" the mid-section. Not to mention their "bumpy bends" they put in the piping which robs power.

On the parital headers (sometimes called a NA downpipe) - mild steel is what you want. I think several places sell them online and they bolt right up between front exhaust collector to the stock rear cat. If you re-use the flanges (see my car pics above), you won't have to cut any of the OEM exhaust piping. It all bolts together nicely.

I got mine used (not sure on brand), but Racing Beat does sell vert & regular NA ones like this:

http://www.racingbeat.com/resultset....tNumber=S16209

 

nice write up, i have a bonez cat from rx7.com on my vert, mazmax here in houston installed it when my brother still owned the car and it is a definite improvement. but i do not know if it had to have a special bend in it or not for that subframe support, i havent gotten under the car to look at it, it could of been custom bent at a shop but i dont know i just know its a bonez cat and it passes emmisions. on another of my s5's i have a 3piece magnaflow cat like the one above, i only use it for 1 day out of the year though, i think the bonez cat is better flowing and better sounding but the difference is minimal, ive been happy with both cats and they have held together. however if i am in the market for another cat converter i think id go with the bonez one from rx7.com.

 

aj one note (jus lettin u know not tryin too flame u) the one above is magnaflows new one piece

 

Correct, the "magnaflow recommend" setup is 3 piece which lasts much longer. We're going with an oversized 1 piece main CAT which is NOT manaflow recommended and trading cat life for performance & MUCH cheaper price.

 

yea one every 2 yrs isnt too bad at 95$ a pop

 

Or making easy swaps for a bolt-in "pre-silencer" or "cat"... for "offroad racing purposes of course

 

of course lol

 

hey what would u sugest as a header/downpipe? for a 87 NA base too eventually get a camden sc and a street port with a apexi gt spec cat back 95mm and 3in cat?

 

Yeah I'm planning an Atkins supercharger setup on my vert. I think converting to the larger piping off a Turbo II would work. Still not sure what to do about header size though. Might call Racing Beat and get their suggestions ... or Atkins might have an idea.

 

alright let me know how it works our because it wont be done for awhile because i want too get my suspension sorted out first and a 5lug swap wit t2 trans so yea itll be awhile lol but it would be nice too get everything worked out ahead of time so it can be set up in stages and so on

 

I was wondering if i went and bought the racing beat exhaust set up and bought full headers and the magnaflow, would i pass emissions in california? And would the 5th and 6th port actuators still manageable with more flow?

 

Oops i just figured out S5's don't use exhaust pressure to open ports...sorry for the noob question =P