Is there any benefit in replacing the up pipe but retaining stock headers?

Cheers

 

Not unless it's an 03-05 Wrx you have, it would also need mapped afterwards.

 

i disagree a correctly matched and flowed up-pipe will give benefits but yes it does require mapped to gain the benefit

 

Will there be any problems/engine management lights thrown up running a decat up pipe, sports cat downpipe on a standard 03 WRX? I've been buying parts to fit to mine prior to a modest remap. Will obviously take it steady until said map is done.

 

Its a P1 I have so no cat on the up pipe. I will be getting it mapped as I will be using a different turbo and injectors on the new engine.

Are they more unreliable though for cracking than OE versions?

 

Nice thread steal lol.
You should not get any CEL errors (assuming you use a PPP downpipe), if you do the mapper should knock them out for you.
You mention a modest remap? If, like me, its sweet running you want rather than squeezing every last BHP why not leave the up-pipe/downpipe and just loose the centre cat (which was what i did). Racedynamix got 280 bhp on that (with filter/cat back). You would get maybe an extra 10 with the up-pipe/downpipe done, but to me didnt warrant the extra dollar...

 

I dont think that replacements are better quality (depending on what you buy).
You can get gains by matching/porting as said above, but very little.
My advice would be "if the car is in bits anyway think about replacing but match/port, if its not in pieces and not broken leave it alone"

 

Harvey up pipe will net you slightly improved spool and performance.
Having swapped it, I gained around 10bhp changing from an H&S up pipe to a Harvey one on stock headers and then having it mapped in.

 

we manufacture & distribute the "harvey smith" trick up-pipes and (bearing in mind i might be slightly biased ) the quality is the best out there

we dont do "one size fits all" and will "match" your spec to a suitable offering

 

Seasoned forum *****

I've already got the items so it's not a problem. I was looking for around 270/280 which should keep the old girl reliable. I wanted to make the exhaust as efficient as possible prior to upping the boost. Have got everything already mentioned plus a 255l/h fuel pump and K&N panel filter.