I think I know but want to be certain before going ahead and ordering parts.

 

Hope I get this right -

Downpipe connects centre pipe to exhaust manifold which in turn connects to the engine. Also known as "front pipe" of the exhaust.

Up-pipe connects exhaust manifold to the turbo.

 

that's what I was thinking. Honest.

 

Up pipe runs up from the manifold to the turbo exhaust inlet and downpipe runs down from turbo exhaust outlet to the remainder of the exhaust system (i.e. centre pipe and backbox)

 

 

Down pipe is the pipe that comes out of the turbo and DOWN to the mid section and the up pipe comes out of the manifold and UP to the turbo..

 

the reason i ask is because i have decatted the second part of the exhaust and stuck an after burner center section and a blitz nur spec r on it. Now I want to decat the down pipe. before adding a panel filter uprated fuel pump and injectors. then a remap. i dont have money to burn at the moment so that's my lot. I'm not changing the headers as i don't want to lose the burble.

I thought for a moment that there was a cat in the up pipe. Am i right that there isn't?

 

If you have a newage there is a pre-cat in the up pipe.. You dont actually need that for an MOT.. to be fair it will pass with just the mid secion cat (last one) and thats the least restrictive one of the lot..

 

WRX has an up-pipe pre-cat, STi doesn't IIRC. It should pass an MOT with either the DP or mid cat. Most who wish to remain legal fit a sports cat DP, but they are pricey.

 

thanks for the clarification guys