I have a 1993 Chev 4x4 regular cab 6.5 diesel pickup and i am looking to add a 4" exhaust most kits i see to buy have 3" downpipe and 4" cat back...well my truck does not have a catalytic converter so do i need to buy just the downpipe and have someone makeup a system from 4" pipe or i dunno anyone familiar with this exhaust system? i need some ideas thanks..

P.S. just seems that cat kits and downpipes are expensive in Canada about $1000cdn minus installation.

thanks,
Shaun