please help, am a complete noob

i have a 3" system, think it stops at the downpipe....

does anyone have any diagrams that could help me, is the downpipe the bit from the turbo?

and whats the up pipe and where is it?

how much will either improve the car and can i have it fully decatted for mot?

 

The downpipe is the large pipe which has a CAT inside that runs from the back of the turbo down to the centre section then onto the backbox.

The uppipe is the small pipe that runs from the bottom of the turbo onto the exhaust headers that run underneath the engine.
If your gonna change the uppipe then you might aswell swap your standard headers for ported ones

Replacing both the uppipe and downpipe will enhance the flow of gases entering the turbo and then exiting it giving better spool up of the turbo.
It makes a big differance just changing the downpipe alone.

But you wont pass an MOT without a cat in your exhaust, so most people save the centre cat and put it back on for when the mot is due.