i have an 07 wrx with a full turbo back decat, sti top mount and fuel pump etc and was remapped with the stock headers and then i changed for stainless steel un-equal length noticed yesterday the heat has cracked my headers and split in two on one of the pipes, i am going to get my stock headers ported and put on back in place of the stainless steel ones is this alright to do? and will it make me lose power or run any different?

 

It will require a map tweak for the ported headers but going from how quickly you say the headers cracked they must have been cheapo ebay jobbies so you will probably get better power from some decent ported headers from the like's of Harvey

 

it'll be better having ported headers i guess than leaving a cracked set on the car and i dont see it making it run bad by doing this or making it a big noticeable difference to anything, yes they where off ebay and they wernt on the car when it was mapped

 

The OEM headers are pretty good if ported......Subaru actually made a few good calls....STi Top mount, induction side and FPR spring to mind

Shaun

 

if they weren't on the car when it was mapped it might even run better, did you notice a difference when you installed the stainless ones and were they wrapped? Let us know if it feels any different when you go back to ported standard chap.

 

'scuse my ignorance but FPR?

 

Fuel Pressure Regulator


Shaun

 

i didnt notice any difference when i put the stainless ones on and they where wrapped, if anything low down the rev range in 2nd gear this only happens on boost it starts to jerk then when you put foot right down it clears and goes and never happens in any other gear ever

 

port your standard ones mate, i was advised not to change to bigger bore stainless ones unless you have a v big turbo and over 400bhp, the smaller bore of the standard ones keeps the gas flow speed up and helps turbo spool and avoids the sort of low rev problem you mentioned

 

cheers im going to use the dremel on them this week and have them fitted and hopefully all is good and runs the way it should, its due 40k service in 3k miles so il be changing the plugs and gear box aswell then

 

ported my own std headers, got better results then my gt spec 2s, same prob, they cracked within a couple years

 

cheers for the advice, did you get issues when on boost with having them cracked or blowing out on the car?

 

If you have cracked headers on the car you are loosing both boost and spool.

 

ll be refitting the headers and up pipe all ported and heat wrapped or ceramic coated

 

If you have OE cast headers you will not be getting them ceramic coated.

 

il just wrap them then, iv got a dremel and iv started to port them, how far down will i take the insides after taking the sooted lip off?

 

There is a lot more to porting than just opening the diameter. We get sets of headers here that are scrap because they have been overported or the port shape is wrong.
At the cylinder head connection open the diameter to that of the cylinder exhaust port or marginally more but the contour should be very gentle and extend as far down in to the header as you can reach. We use air operated tools with flexi drives and each port in and out is an opportunity to accellerate gas flow.
Also do not forget the uppipe. You may as well throw away the standard Subaru item and obtain a well designed aftermarket item such as the one we supply. This will make a big difference in addition to the porting.