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wazza16v
22-12-2006, 11:21
Hello there just a quick question on de-cats, i did notice a difference on the sound of my car when i replaced the cat with a de-cat, but it seemed to be a bit sluggish on pull-away.I was thinking it might be a to do with the lack of back pressure from the exhaust, does fuel economy get reduced and by how much?

Tommo
22-12-2006, 11:46
Didn't notice any difference in fuel consumption with my decat on mate, but much prefer it with the cat on tbh, more torque lower down the revs, I think it is to do with back pressure. I do miss the sound of the decat tho...

wazza16v
22-12-2006, 11:59
I will put the cat back on once i get a chance, but i will componsate the noise loss and put the induction kit on as it freezing out there :D

Tommo
22-12-2006, 12:17
Not many people run a cat on here (think I'm one of a few), but my car just seems to run better with it on so I left it that way after the last MOT, still got the decat in my shed!

wazza16v
22-12-2006, 12:21
:-$ don't tell anyone but this might improve my quarter mile time at santapod, u never know my launch might be improved with more botton end torque. :wink:

VIPERONE
22-12-2006, 12:55
i run a cat...it makes your car feel quicker..but i know for certain the midrange grunt is alot more with a decat.

wavy
22-12-2006, 15:13
im still using a cat because of the reasons above
lose 1 bit of grunt to gain another
i might try a decat after my next mot(april)

Andyvalver
22-12-2006, 15:18
Ive been running a de-cat for a few years now. Main thing i noticed was it pulled better at higher speeds 3rd gear onwards. It seemed no better below 60mph really. Sod the low down grunt imo, mines always on the boil anyway :twisted:

Daz.
22-12-2006, 16:06
I run a cat - leaving it on I think... power can be gained elsewhere :twisted:

VIPERONE
22-12-2006, 19:24
. Sod the low down grunt imo, mines always on the boil anyway :twisted:


you thought about changing the coolant, and installing a low temp fan switch/thermo? ;-) :wink: :wink: :wink: :wink:

Andyvalver
22-12-2006, 19:28
. Sod the low down grunt imo, mines always on the boil anyway :twisted:


you thought about changing the coolant, and installing a low temp fan switch/thermo? ;-) :wink: :wink: :wink: :wink:


:lol: You know what i meant :wink:

richy
22-12-2006, 19:59
didnt notice any difference to bottom end, just top 3rd gear on it pulled much better, anf of course louder!

MatBrown
22-12-2006, 20:06
I run a cat cos the de-cat was too loud with the devil straight thru mid section.
Got a brand new renault cat to fit when i get the car on the road.



Mat.

richy
22-12-2006, 20:13
I run a cat cos the de-cat was too loud with the devil straight thru mid section.
Got a brand new renault cat to fit when i get the car on the road.



Mat.

lol i had decat with devil straight thro system! took devil off in end due to rotten and way to loud! scorpion sounds just right!

nyk
22-12-2006, 20:18
I have a de cat, but it was replaced with a free flow box of a pug 205 to quieten it a bit. I dont like it too loud, on a magnex cat back system.

Noticed a slight difference, nothing major, difference is from about 3rd upwards.

:lol:

Mr.AdamB
22-12-2006, 20:23
decat improoved my valver alot. alot better top end acceleration also i diddnt

end of the day decat = ure car slightly faster!

i getting RR asoon so we see how muhc extra bhp i got from a decat! and expect to gain sum tourque as well!

Mattie
23-12-2006, 20:04
i like the sound when the cats on....with a decat on my straight through system its 2 LOUD....but i think the cars more responsive with the decat on....i noticed my williams had trouble pulllin when higher up in the rev range.....just took my cat off and had the de cat put back on 8)

MattyH16valver
23-12-2006, 22:01
I notice quite a difference when I put my de-cat on my hybrid...seems to pull away better...and better through the rev range. Motorway driving can be very load though on long trips, but again, acceleration seems better. On my willy, the cat is still on and it does sound nicer, but feels restrictied, so i'll try it with a de-cat soon. Generally though I prefer the de-cat as I don't do too much motorway driving. Matt

Hulio
24-12-2006, 04:27
My hybrid also seemed improved when i put the de-cat on. That nasty cat was slowing me down!

Purple
24-12-2006, 05:41
IMO, I think for standard engine tune, the cat keeps up the backpressure at lower revs while still being quite free flowing at higher revs. But for engines that runs stronger than standard, the backpressure might be too much especially at higher revs, so removing the cat allows for a freer air-flow.

I think it's all down to proper tuning. Just borrow someone's decat to try.

Laine_16v
24-12-2006, 12:19
Decat was good on my last valver, increased its top speed by 7mph on the dials!

wazza16v
24-12-2006, 12:37
Decat was good on my last valver, increased its top speed by 7mph on the dials!


7MPH Everone knows the valver dials arn't accurate, and did you find that out on a private road ? :wink: :wink: :wink:

Mr.AdamB
30-12-2006, 16:15
my decat has given me 9 lbs of tourque and 9 bhp ontop of standard figures! has it RR the other day. :)

u33db
09-01-2007, 13:45
I run a cat cos the de-cat was too loud with the devil straight thru mid section.
Got a brand new renault cat to fit when i get the car on the road.



Mat.

lol i had decat with devil straight thro system! took devil off in end due to rotten and way to loud! scorpion sounds just right!

I had decat with the straight through centre section too...was definately loud! You could hear the gases running though it near tthe gearbox at idle which was pretty cool tho... :)

Laine_16v
09-01-2007, 13:49
Decat was good on my last valver, increased its top speed by 7mph on the dials!


7MPH Everone knows the valver dials arn't accurate, and did you find that out on a private road ? :wink: :wink: :wink:

Im not talking amount, im talking about increase, for which the dials are fine.

Swervin_Mervin
09-01-2007, 14:46
Mine will soon have a de-cat, although I might still investigate the sport cat route, having got one for the Xsara. Made a noticable difference on that, but more in terms of ironing out a few flat spots.