you can change out the 87-96 spirit exhaust pipe bracket on the frame near the swing arm for one that is for a 97+ spirit or sabre and be compatible with those stock pipes or after markets fit to them. however, i don't think you will succeed in finding another make that will work...IMHO.
mario, there's a lot of stock pipes available or eventually available on Ebay etc. After owners upgrade to an aftermarket pipe, many try to sell them online, etc. I suppose the same on your continent.
Anyways, try the links below to get you in the general ballpark of what Shadow 1100's exhausts are similar to yours. Of course, crosscheck the various mufflers on Oem parts websites to verify that do indeed have the same product numbers. Or, perhaps they're shaped close enough that only the backside brackets requires some duct tape. Disclaimer, *range of years* listed below are approximates.