some info required please,

1. what is an up pipe and what does it do?

2. is it essential to replace the std one when remapping or just another step you can take?

3. what sort of gains are achieved?

4. is it alot of work (cost) to change one?

5. can the car be happily remapped with other normal exhaust mods in place with minimal bhp/torque difference? (if any)

ta

 

STi doesnt have a cat in the up-pipe so no not required to change it. If doing down-pipe then check it for any signs of cracking while ur there but on an 05 I doubt you'll have any problems.

This pic explains the system well
http://www.scoobysport.com/images/exhaust/flow.gif

As for the rest of the exhaust system for a remap it's usually recommended to remove as many cats as you feel comfortable with and replace the back box. PPP will replace downpipe cat with a sports cat and remove the centre cat, so that gives you an idea. Oh, and K&N or Green panel filter will see benefits too.

 

thanks for thatsaves hunting down one of those then buying the bits over time for when the warrenty runs out, got prodrive b/box and de-res pipe already with a PPP downpipe on the way

usefull pic aswell, even i understood it