What are the differences between a downpipe for a 1.6 and one for a 1.8?
I was looking at the used 1.6 SG downpipe on BEGI's site. I need it for my 92 with a 2000 1.8 or my 94 with a 1.8. Not sure which car/motor I will be using for my build. I have access to a fab shop for mods if needed.

 

i wouldn't think there'd be a problem adapting it. 1.6 and 1.8L manifolds put the turbo in a near identical spot.

 

It seems like the downpipes should be nearly identical. If the trans is in the same place the cylinder spacing on the 1.6 would set the turbo back very slightly, so maybe the 1.6 downpipe is a little shorter overall. Shouldn't be by much though.

 

I understood the difference had more to do with the overall length, ie getting back to the stock position of the cat was significantly different on the 1.6 and 1.8.

 

correct, and angle to boot.

 

A 1.6 dp with a 1.6 cat/test pipe will bolt up to 1.8 exhaust.