..On my 05 WRX for 280 bhp-ish..???

de-Cat downpipe - [£99].
SS Subaru deCat Up Pipe. [£60ish].
deCat Mid-Section - [Got.]
Walbro 255 fuel pump - [£70ish]
NGK PFR7B plugs - [£30]
K&N ‘Cone’ filter - [£40]
ECU Remap - [£350+]
1 question, will it pass MOT if I LEAVE Up-pipe on but swap both deCat pipes or is it just as easy for mechanic to swap all?
To push it to magic 300bhp mark what more would I have to do?
ta.
J

 

Hi, that little lot would see you in the region of 280bhp. AFAIK the uppipe cat wont be enough to pass the MOT, it is much better to add a decat uppipe as it will help the turbo to hold boost at high rpm (thats what Bob Rawle told me when he mapped my car), my car has a sports cat downpipe and it passes the mot just fine.

in order to get past 300bhp, you will need a bigger turbo, either a vf34/35 as a minimum, however you could add in larger capacity injectors and an STi top mount intercooler.

Hope that helps

 

the above mods will see you somewhere in the 270-280bhp mark, your car wont pass the mot with just the up-pipe cat, you will either need a sports cat downpipe or a decat friendly mot tester

to get to the magic 300 you will need to upgrade the turbo, intercooler,injectors and remap again aswell as the above mods

 

And go panel filter not Cone !

 

I think Iain needs to re-read your post...

You'll pass the MOT without up-pipe cat in the same way the STi does.

Easiest way to pass the MOT is to keep the turbo back 4 piece and replace the underfloor de-cat with a cat for the MOT, changing the DP is a pain.

Simon

 

think he was asking if it will pass the mot with just the catted up pipe in place

the only way ull pass the mot is with the downpipe cat in place or sports cat, you wont pass with just the centre cat or up pipe cat alone

 

Yeah I though he was asking if it would pass the MOT with just the uppipe cat in, which it wont, thats all!

 

280 should be achievable on those mods (ditch the cone filter though and use a panel filter instead).

The up-pipe is a git to change and I would leave that til changing your turbo - you will need to change turbo to something bigger to get over 300.

You could consider a sports cat instead of a full decat though and still be MOT friendly for a little decrease in total power in return for the lack of hassle at MOT time.

 

Many thanks for all the input.

OK, so. Just to clarify on the exhaust front, I either:-

a) Install a standard deCat downpipe and deCat mid-section, but, come MOT time, the mechanic will have to swap these sections back to my standard setup (downpipe being a bugger to swap).

b) ..or install a SportsCat downPipe ONLY (leaving the rest (midCat) as standard), that way I’ll still get nearly 280bhp but it will pass the MOT straight away?

c) ..or install a SportsCat downPipe and deCat mid-section, that way I’ll definitely get my 280bhp, but it I will have to replace mid-section only come MOT which will be an easier job.

Sound about right? Any other advice?

Thanks again.
J

 

Sports cat on it's own will pass mot

 

Like Duncan says J, I only have a prodrive sports cat downpipe in my car, rest is decat including uppipe and have passed 2 MOT's like this

 

or fully decat and find a nice mot tester

 

Got my car true the mot last mounth with a full decat
at saying that the car was mapped in march by JGM

At the time my05wrx was runing a full de-cat,550's, pfr7's,
hks panel filter, HDI 3 port, sti8 intercooler and a front entry td05 16g,255l fp
and made over 300bhp

just fitted one of Harveys GT2 frontmounts with the cold
air kit (AEM filter) tweaked by JGM on thursday
and made 341/329.

 

View my car - I have similar mods with Prodrive Sports Cat downpipe. Passes MOT without changing anything.

As has been said though, you won't get 300BHP on standard TD04.