Cats and stuff

Whats the advantages/disadvantages of having cats on the downpipes of a legacy? should i get the pipes with or without cats?

Cheers

PROS are if you green consious and nct purposes and possibly more fuel efficent...
CONS are power restriction i suppose

power restriction in what way, or how does that work??

as far as i know the cat has to clean the exhaust emmisions and by doing this it slows down the flow leaving the engine, when removed the flow is no longer restricted resulting in power gains. i dont know if the cat burns off the emmisions or somehow filters them but it does slow down the flow

[quote author=nicknack link=topic=13192.msg162461#msg162461 date=1235833802]
power restriction in what way, or how does that work??
[/quote]

there shouldnt be any power restriction, the only thing is the exhaust will be quiter compared to it being decatted .

you would have more power with a decat pipe as there is no cells to sort out the gases and your turbo will spool up quicker with it, you might get a small bit of boost creep with a decat, mine has a bit of boost creep

[quote author=northdublin link=topic=13192.msg162465#msg162465 date=1235834314]
as far as i know the cat has to clean the exhaust emmisions and by doing this it slows down the flow leaving the engine, when removed the flow is no longer restricted resulting in power gains. i dont know if the cat burns off the emmisions or somehow filters them but it does slow down the flow
[/quote]

I'll second that :lol: had the two cats taken out of my leggy and instantly noticed the gains,quicker spool up from the small turbo but you need to get a tweak map to get the most out of it if you want to take my leggy for a spin to try it your more than welcome

If your unsure get a sports cat which will improve flow and pass the NCT

well its gonna be put through the nct as is, as it passed before, but would just hold onto the pipes for next nct or whatever ya know!

@ b4_rsk, is yours mapped and all? which 2 cats did you get taken out?

there shouldnt be any power restriction, the only thing is the exhaust will be quiter compared to it being decatted .

you would have more power with a decat pipe as there is no cells to sort out the gases and your turbo will spool up quicker with it, you might get a small bit of boost creep with a decat, mine has a bit of boost creep

[/quote]

if you have more power with a decat,does that not mean that the cat is a restriction????

cat wont affect the exhaust noise,thats the job of exhaust baffles and boxes!!!

[quote author=markobucko link=topic=13192.msg162471#msg162471 date=1235836849]
there shouldnt be any power restriction, the only thing is the exhaust will be quiter compared to it being decatted .

you would have more power with a decat pipe as there is no cells to sort out the gases and your turbo will spool up quicker with it, you might get a small bit of boost creep with a decat, mine has a bit of boost creep

[/quote]

if you have more power with a decat,does that not mean that the cat is a restriction????

cat wont affect the exhaust noise,thats the job of exhaust baffles and boxes!!!
[/quote]

i suppose it does

i forgot to edit it, what i meant was it wont be as loud with the cat in it

[quote author=nicknack link=topic=13192.msg162469#msg162469 date=1235835184]
well its gonna be put through the nct as is, as it passed before, but would just hold onto the pipes for next nct or whatever ya know!

@ b4_rsk, is yours mapped and all? which 2 cats did you get taken out?
[/quote]

Yep tweak mapped there a couple of days ago by Bob Rawle i got rid of the cat on the downpipe from the first turbo and the centre section cat,the sound is much deeper and she now has the scooby burble