Sports cats - cell count

[yeti]

Looking at fitting some sports cats to the 996 3.4 as I have had good results with every car I have ever done it to - standard stuff is restrictive beyond belief! Can I get away with 100 cell cats or do I need 200 cell? Difference is £70+ so it matters, however I don't want to fail the MOT on emissions or flick up an engine chack light if I went for 100s.

Any thoughts?

Edited by yeti on Thursday 1st December 15:24

[MrCooke]

Get 200s.

[yeti]

MrCooke said:

Get 200s.

Why?

/as we're doing short answers

[mrdemon]

how many cats are in those as standard

I deleted 2 of the 4 cats in my cayman S and also 2 of the 3 cats in my TTRS with no issues and more power.

you only need 1 to pass the MOT so get a 200 cell sports cat and remove any others.

[yeti]

mrdemon said:

how many cats are in those as standard

I deleted 2 of the 4 cats in my cayman S and also 2 of the 3 cats in my TTRS with no issues and more power.

you only need 1 to pass the MOT so get a 200 cell sports cat and remove any others.

MrD! 2 cats as standard, one per bank, so both need to be replaced. Question is whether I can get away with 100 cpi or I need 200cpi to pass MOT and not throw up a check light. 100cpi cats come from the same supplier as the manifolds (Porscheshop) rather than the Design911 ones which are quite a bit more money. Just trying to make it all easier by dealing with one supplier and save on packaging and carrying stuff home!

[MrCooke]

yeti said:

Why?

/as we're doing short answers

Cos of what you said.



Or in more detail; I've had 3 996s with 100 cell cats from 3.4 to GT3 and all of them have put the management light on. One was OK on the MoT, two weren't. There are manufacturers that says theirs are OK and the may well be, but I'd not risk my hard earned for the minimal benefit.

[Ian_UK1]

MrCooke said:

Cos of what you said.



Or in more detail; I've had 3 996s with 100 cell cats from 3.4 to GT3 and all of them have put the management light on. One was OK on the MoT, two weren't. There are manufacturers that says theirs are OK and the may well be, but I'd not risk my hard earned for the minimal benefit.

Agreed. Definitely use 200-cell. The difference between 100- and 200-cell on a roadgoing 3.4 will be absolutely minute. A pair of HJS 200-cells in the diameter most tuners use for the 996/7 will flow 400BHP without any substantial restriction whereas the 3.4 996 engine will only go to about 320 BHP max with bolt-on mods. (You need substantial head work and cams to take the engine further). Using 100-cells will give at most another couple of BHP over 200-cell on this engine - not worth the hassle of CELs and the time/cost of reprogramming the ECU to stop them.

[tangoecho]

HJS 200cpsi, defo.

[yeti]

Thanks for the detailed answers guys, 200 cpi it is.

New manifolds, the cats, CAI with panel filter and I already have sports back boxes... if that gives me close to 320bhp and sharper throttle response I'll be a happy chappie!