993

[boost]

hi guys looking for abit of info ive just purchased my 993 and was looking for some info on exht mods and what is good what is bad.the car is stock apart from a chip a good friend of mine james o connor has just loaded, not doing to much to this one just subtle mods.

[Bill Verburg]

I am pleased w/ Fabspeed cat bypass pipes/stock mufflers


I also have a set of modified RSR mufflers but they are very loud when used w/ the bypass pipes.

[Jbabic]

Cup exhaust....Call me and I will start my car up and rev it...loud, but not too loud...I always get complimented on teh exhaust...easy to install, remove mufflers and install the pipes...

[Bill Verburg]

This is a Cup exhaust


If that is what you have yes, it sounds great and loud. Many race tracks won't allow it, let alone the local constabulary.

[boost]

with the cat bypass pipes how "drowny" does the sound noise get ? and is it that much of a gain as i assume the cats are a stainless item and should flow.an obvious mod would be a k&n filter ?

[Bill Verburg]

"drowny"

I Fabiani cat bypass on mine, w/ stock mufflers the sound is fine very livible, won't attract too much attetion from enforcement types, it still sound great.

W/ RSR type mufflers it is much louder.

Bypass w/ RSRs

Bypass w/ stock mufflers

My 3.8Rs w/ heaaders & Flowmaster

random Watkins Glen Historics

another WG

and another WG

[aigel]

What is the power gain from removing catalytic converters?

Thanks, George

[Bill Verburg]

Here is a '95 non vram motor / Fabiani cat by pass, 94,000mi



I have seen quite a few vrams w/ cat that don't do as well

[aigel]

Bill,

That's what I heard, that the variorams do not benefit much of it. Just wondering if I could get some extra (cheap 'n easy) power for the track. Looks like it sure wakes up the 95, especially if it has no other modifications.

My engine has a chip and RS runners and it dynoed at close to 280 at the wheels, if I remember right.

Right now I am enjoying the car and the fact that tere is no wrenching, just driving, so any changes would be more long term.

George

[Bill Verburg]

Originally posted by aigel
Bill,

That's what I heard, that the variorams do not benefit much of it. Just wondering if I could get some extra (cheap 'n easy) power for the track. Looks like it sure wakes up the 95, especially if it has no other modifications.

My engine has a chip and RS runners and it dynoed at close to 280 at the wheels, if I remember right.

Right now I am enjoying the car and the fact that tere is no wrenching, just driving, so any changes would be more long term.

George

This is what I detest about these dyno postings, you cannot compare 1 w/ another, I regret posting that one. They are only useful for comparing cars on the same dyno under the same conditions w/ the same gears and correction factors in place.

I only posted that because it was very healthy relative to 2 vrams w/ cats done on that same day.

[aigel]

I know what you mean. Even the same dyno is questionable, unless you do it within very short time spans. I have dyno sheets for my car that varied more in readings taken at different times than the modifications warranted.

Basically I'll just have to get the bypasses (?) and do a before after. That gets expensive quick. For now, I am driving!

George

[Bill Verburg]

Originally posted by aigel
I know what you mean. Even the same dyno is questionable, unless you do it within very short time spans. I have dyno sheets for my car that varied more in readings taken at different times than the modifications warranted.

Basically I'll just have to get the bypasses (?) and do a before after. That gets expensive quick. For now, I am driving!

George

That would be interesting. I hope to have back to backs on my 3.8RS w/ B&B vs stock and the 3.6 w/ stock vs B&B later this winter. All would be done on the same dyno.

I don't know if you have ever opened up a 993 cat but they use a mixing chamber design. It is excellent at slowing down and inducing turbulent flow to the exhaust gases. It is excellent from an emissions perspective but terrible for flow and performance. The separate pipe Fabiani setup up is the correct way to go(IMO). I found them too noisy w/ RSRs but just about perfect w/ stock muffs

[boost]

what i will do is dyno my car b4 and after i fit cat bypass pipes on same dyno hopefully this will show if they make a difference and how much.hopefully in the next couple of weeks

[aigel]

Sorry to drag this out, but reading about the turbulences in the stock setup, I am wondering if there is high flow cats that can be adapted to the 993? It would be nice to keep it legal for on road use here in CA.

George

[Bill Verburg]

Originally posted by aigel
Sorry to drag this out, but reading about the turbulences in the stock setup, I am wondering if there is high flow cats that can be adapted to the 993? It would be nice to keep it legal for on road use here in CA.

George

Sure, the 100 ror 200 cell cats set up ike onthe GT3work very well also, very expensive though.

Honestly, MO after having done the 3.8RS thing and regear thing, gearing, especially from the stock G50/20 is huge.

[aigel]

Yes, you are already preaching to the choir in terms of regearing. It is an expensive upgrade but makes perfect sense. I hate second, especially in AX.

George