i have a H&S decat to put on my 04 sti ppp but now im wondering weather to just leave the ppp one on as ive heard theres not much gain to be had. but now is the time to decide as its off to bob very soon. so on the whole what do we think ?

 

i've heard as little as 2bhp in some cases don't know how true, although tsl recommend the sports cat, if this helps

 

I would be inclined to leave the PPP one on as already said little gains to be had with a decat over PPP.
It would also depend on what other mods you have and wether the decat/your exhaust is 3" and what other mods you have as I expect a 3" over the PPP would be more suited if you are going over 350.
If you are visiting Bob Rawle for a remap best asking him.