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cutting out cat;s on diablo

5K views 21 replies 9 participants last post by  abunawafff 
#1 ·
hi guys
i heard that cuting out the cats, and replacing them with strait throught pipes gives more HP??????
is this true??? what are the imediate efects??? and what about the sound???
im thinking of having that done to my 98 SV. and i realy dont have a problem with sound... :D
 
#3 ·
You will see some extra power; nothing necessarily in the 'seat of the pants' though. You will have a significant increase in noise accompanied with excessive popping and flame-throwing on deceleration. If you mod your car for more power then the power increases will be more significant. You may want to get a ceramic high flow cat which will almost negate the power increase, give you a reasonable increase in sound, and elminate the flames....but to each his own..
 
#4 ·
I installed a Larini System on my 98 SV. Removed the two rear cats. Leave the other two. No problems, Snarling sound, a little burbling when you let off. It's really the way the car SHOULD sound with a real exhaust note instead of a "machine" sound, and it just breathes better. Better performance, I say yes, but I didn't measure it. You'll save about 35 lbs removing the stock muffler too.
 
#5 · (Edited)
spelling

morphdj said:
check your spelling on your location details, "Location: where lambo's are like swatches.......they where them for a while then..."

do you mean "wear" them for a while ? sorry :p



i thought this was a forum for lambo owners to gain from other owners expireance???
who cares about spelling??? as long as U own the actual car?????? :wave: :whip:
 
#6 ·
For many people here, English is not their native language, so I don't worry about spelling. Try posting on a German web site in German...

Anyway, to the original question... I echo Raymond.
Depends on the year of your car. Late model cars with 4 cats can pull the rear two cats. I have an early car and tried a variety of cat replacements. A straight pipe was too lound and too much popping from reduction of back pressure. I then installed a Qucksilver silenced test pipe. That was very quite and the car sounded identical to stock. I then tried the original cats, but had them hollowed out (insides removed) and that is the sound I like best so far.

Removing the cats will give you slightly more power & reduce engine bay heat - cats put out a tremendous amount of heat. Also change the muffler, the stock muffler is very heavy. I went with a Tubi and I think the weight saving is closer to 50lb..

I have not Dyno'ed the car, but changing mufflers and removing cats on a Diablo should give you around 20-25 more horses, but more importantly your car will run cooler and better.
 
#8 ·
thanx for explaining it to me FL355 i think il do just that take out the back cats..and get a new mufler... oh and its a 98 sv ...so its less heavy than the rest of the models.. :) :D
and thanx hazim i hope ur enjoying that black beuty u have parked in front of ur place :wave:
 
#11 · (Edited)
OH MY GODDDDD

got my car back from the shop...the mufflers are out...and ran straight pipes...the car sounds incredibly laoud and frightening :eek: ..... cars move out the way when they hear it. :D ... and when driving down my street the sound sets my naighbors car alarm's off.. :headbang: .. its funny realy... and i know all the area hears me coming home from dinner...looool


but i love it... :blob:

Hell, it sounds like a true Bull..on steroides.....and i can feel more power...it is very notisable when i drove back from the shop.....but that might also be becouse of the less waight

any coments... does any one have this setting in there diablo??
 

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#15 · (Edited)
raymondo said:
No offense, but that's kind of a rough looking installation.

yess ur right...but... my freinds 94 diablo has had this same thing done (from new) by the same person , and he drives it all the time.....his car is in top shape....


and if i tell u the cost, U might not get ur eye brow high enoughf... :evil:

the car sounds amaizing......i mean Ferrari Enzo Kiss my A$$ amaizing.. .. :eek: ..

but at start up...it is frightening...lloooll .....then the beast settels :D


p.s. my golden rule = dont do something to the car , u cant have redone to original.... :wave:
 
#20 ·
abunawafff said:
turnes out the rear cat's were removed already

im having the mufflers removed today...replacing with straight through pipes

and ive ordered the 2 end pipes from tubi

so il let u guys know how it turns out...but i know its going to wake up the whole area QUOTE]

I am an exhaust designer.
It's interesting what you are doing, but LOUD does rarely mean more power.
It's often symtomatic for flat spots, poor part throttle driveability and high fuel consumption.
If I were to design you an exhaust, I could get more power for you than you currently have with a 30dBA decrease in exhaust noise (enormous) WITH catalytic convertors, but a 15dBA increase in induction noise-which is obvious signs of an engine breathing a lot deeper.
I don't mean to spoil the fun, but my taste is for cars that are quiet and go like stink....it may cost a lot to do things properly in thin stainless, inconel and titanium but the results are astonishing.

In F1 it's true we go for all out power, the costs are obscene and the waste is to my mind equally loony.
I actually do work in F1 in the past+single seaters now, but again, the only exhaust designs which have been ultimately successful were those for the HONDA V12 F1 the Lamborgini 3.5 F1, and the cancelled (orphaned) Cosworth F1 V12 project.
Those were just VERY GOOD ENGINES to begin with.
All the others were V10 designs starting with the RENAULT RS series up until last season.
My morale of the tale:- The world is a very small place. ;)
 
#21 ·
GT 12 - Very well put.

I think there is a preception that straight pipes and loud = power. Not always.

As I understand it, exhaust speed, not back pressure creates power. Usually, they go hand in hand, but not always. You need a flow bench to determine the best design.

Sometimes, a little back pressure can be a good thing, I know on my previous PTurbo and F355 totally eliminating back pressure results in slight loss of torque on the bottom end.

If you're interested in building a custom exhaust system for a Diablo send me a PM.
:)
Frank
 
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