Thundercat downpipes

Hi. I am new on here despite owning my Thundercat since I was 19yrs old. I have not had it on the road for two yrs since I bought a new Honda 600rr and now want it back on the road! It failed an MOT last yr on rusted downpipes and have just taken them off etc and am looking for replacement ones. Does anyone have anything to offer on replacement ones in terms off what to get. I know some people say aftermarket ones don't always fit easily!!!! I would buy replacement non stainless if necessary. I would be doing arounf 500 miles per year at best!!

I look forward to hearing what people think.

Thanks

Rob