I have decided I am going to remove the cat ( the one on the downpipe from the turbo) which will give me a turbo back decat system ( at the moment I have a very nice cat back system that I don't really want to get rid of) , what I could do with knowing is which one to go for, I have heard that you loose spool up time if you get the wrong one, ( ie the £100 specials off ebay which all appear to be the the fully open type at the turbo) I will be looking at at remap very shortly after doing this but want to make sure I am not loosing power through the wrong choice.

Also has anyone just removed the cat from the standard pipe and welded in a straight through piece of pipe,or modded one that does produce similar gains?or a waste of time?
sorry lots of questions but I'm on a tighter than tight budget ( for this read skint)
as ever thanks for reading and before I forget, I have a 52 plate wrx whch is currently running a cat back zorst and standard airbox with performance panel filter,
cheers
Baggy

 

the problem with removing and welding a pipe in, is that you retain the wastegate path of the original which is far from ideal.. the exhaust gas has to do a 90degree turn out of the wastegate and hits the exhaust gas leaving the turbo's exhaust wheel at 90degrees too it causing massive back pressure.

open mouth downpipe is the way to go.

Simon