SIP road exhaust for GS160 bored to 200

Hi, seeking some advice on which SIP road exhaust I should use. I have a GS160 with standard motor bored to 200 and running a PX200 piston with transfer welded up. Are the SIP road exhausts build to match the engine capacity? I guess the real question is - do I buy the exhaust for the GS160 ...or the one for PX200 and have the exhaust modified for the engine exhaust stub configuration. Also is there a suitablel piston for 200cc piston port conversions that doesnt need the welding job? Thanks Phil NZ