I am trying to avoid EM as much as possible on my 05 wrx as there aren't any preferred turners near where I am based.

Will the car still get boost spikes issues if I use a DP with hi-flow cat (what i reckon is at least a sport cat is present)?

Am I thinking in the right direction that only when the cat is missing from the DP or UP, the ECU will notice and therefore throws DETs or CELs?

It is interesting to see if a DP with hi-flow cat on a 04 - 05 car can be the solution to DETs, CELs and over the top EGT after some decats. Are there anyone out there who has a set up like the above and wouldn't mind sharing your result with us?

Your input will be much appericated. Thanks

 

Removing the centre cat on a WRX and straight through from there is no problem. Doesn't pull off that nicely from very low revs but no real issues.

I think that even with a sports cat downpipe and especially with the up-pipe you should have it remapped. A decent sports cat downpipe will flow near the same as a de-cat downpipe - the H&S d/p only loses 2-4bhp over a decat d/p. I would expect overboosting if you didn't map it and the problems that come with that when it's serious. Would want a boost guage as a minimum.

 

Hi Ben

Will removing the last cat on the centre section reduce the pull from very low revs? below 3000rpm?

or is it increase the pull?

 

I found with the centre cat out and straight through centre plus back box sections that the car didn't pull off so nicely in stop start traffic for example. Lost a lot of pull below just over 1000 rpm - but get used to it quickly and not a big issue, just use slightly more revs pulling off.

 

Oh is that right! Thank you for your insight and I respect that.

But, can you explain why there would be less pull lower down the rev range? Shouldn't it have a better pull?