You will not be able to sue, (and win), in small claims court. As stated above they will intially low ball you, but you are permitted to counter with whatever you "feel" is the value of the bike they may come up some, or they may not. In the end if you disagree with the value, you can file a complaint with the TD Ombudsperson, and evenutally esculate it to FSCO.
But if you go the small claims route and lets say they offer $5,000 and you sue saying the "true value" is $8,000, you will have to prove why your valuation is more accurate, than theirs. IE being able to produce legit reciepts for the items you "claim" were on the bike. Having text messages with a tech about a power commander m=are really meaningless, as you can PROVE the part was still actually ON the bike when it was stolen.
Just because you may have paid $500 for a part doesn't mean that that adds $500 to the value of the bike, (unless it was installed the week before as a brand new part). The reason they want receipts is to pinpoint a reasonable value. A Power commander might be worth $1000 brand new, but if it was on the bike for 4 years it is no longer worth $1000. How can they confirm the age of the part without proof, (receipt), that it wasn't a 10 year old part your buddy gave you when he sold his bike 2 years ago, or that it actually EVER existed? Or that the exhaust was intially $500 new but you bought off kijiji, after someone bought it installed used it for 2 seasons then stripped the bike and sold the exhaust you for $50? Should they give $500 for a $50 part??
But your getting way ahead of yourself, you should at least wait and see what they offer and how receptive they are to your counter, before deciding to go to small claims, (where they can, If they prevail, ask you to pay their legal fees).