hi

is it safe to upgrade to aftermarket exhaust headers on MY98 uk impreza with PPP? (old one is blowing somewhere)
if yes should I also go for maching up-pipe?
are sti headers are the some as standard ones?

cheers

 

yep perfectly fine, depending on what you go for you may notice a difference in spool and noise characteristics but thats about it. classic headers are all the same. ppp doesnt matter

may be worth 'spending a bit more to upgrade' and gettin a ported set from Harvey smith (do a search, v highly regarded)

 

PPP does matter, its a custom map, changing anything from that spec means you should remap the car to suit.
Unless your going to remap the car (your going to need an after market ecu to do so as yours is an MY98 car) its probably not worth upgrading.

Tony

 

custom, what so when everyone bought their ppp they had it mapped after purchase? or do you mean a generic map for all the ppp's?

 

Its mapped for the parts that are on the car already, change any of those parts to none standard and you can be asking for serious issues.

Tony

 

It might be "safe", but it might well not be. Either way it'll probably make your car worse. You will almost certainly need a remap to get the best out of aftermarket headers, and in any case, many of them - especially the cheap mass produced ones you find on eBay and similar places - are optimised for larger turbos and higher power outputs than your TD04 is capable of delivering. So even with a remap you are likely to lose a little (or more) low end response and spool.

If your existing exhaust manifold is leaking somewhere the best solution would be to locate the source and replace the offending part with another standard one rather than chuck the whole thing and fit an aftermarket set. It's most likely to be the flexi joint in the cross- or up-pipe, or somewhere else on those two items. If it's a significant leak the soot that will be blowing out should make it fairly easy to spot.

If you did want to replace the entire manifold the best replacement would be a ported standard set from Harvey, either with a standard up-pipe or his small TD04 optimised one.

If you're asking whether classic STi manifolds are the same as non-STi ones for the same model year, the answer is yes, although there are differences among the model years.

 

 

thanks for all replies.
I will try to locate the leak and replace the part.

 

imo you could get away with it, sure it might affect spool or something, but to get the best from aftermarket stuff of course it has to be mapped in so it all works together

mine arnt mapped in, so hope my car doesnt spontaneously combust before mapping

 

Do not fit aftermarket headers to your car if you want best spool.
Best option would be to port your existing headers and run with a performance purpose designed uppipe to suit your existing spec or take into account the possibility of changing to a bigger turbo. Just as advised by Splitpin.
Ported headers with a matched uppipe, DEI wrapped and five new studs is £369 exchange and we can fit for £75 which is a bargain. At that point you have no exhaust leaks and a much more willing, responsive engine with more torque right across the range.
If you don't want to make the trip to Darlington we can send headers out in advance so the downtime on your vehicle is kept to a minimum.