urgent help please! So I've got my old system off of the car and I'm now trying to fit it back with a new non res section, cobra second decat and mating it to the standard downpipe. I bought a genuine subaru cone gasket to sit between the non res pipe and 2nd decat but the cone is either too small or the decat is too large.. By about 2-3mm! Does anyone have any suggestions? :/

 

have you got the correct pipes? 2.5" ? or have you bought 3"

 

It's a 2.5" pipe which is the correct size, says diameter is 63.5 on the metal work. This is so frustrating!

 

doesn't the non res pipe connect to the second decat with a normal flat gasket ? the second decat pipe should mount to the down pipe with the cone/ring one

 

It's the other way around - see item 15
http://workshop-manuals.com/subaru/impreza_wrx_sti/f4-2.5l_dohc_turbo/engine_cooling_and_exhaust/exhaust_system/muffler/component_information/service_and_repair/page_1486/

It isn't like I can widen the gasket without not compromising its strength