Hi Oldbiker, and welcome to the forum. Which exhaust can, will present you with endless suggestions. Nearly all come with a removable baffle and suitable link pipe, so you have a choice of in or out, no doubt in, when it's mot time. You've got choices on length and material, shiny or not, expensive or not. Unless you see/hear one on another Fazer that floats your boat, then it's a matter of checking out the manufacturers websites and looking around for the best deal. Personally I've used SP Engineering twice now, for the two different systems I have, and have received favourable noise comments.
Decide on the look you want and take it from there. In your post you mentioned the A3, which end are you near?.