With the GPZ1100S & GPZ500S found that there is very little after market for them, especially in the UK.
With exhausts it's either Motad or Laser which are both at the cheaper end of the market. The original system on the 1100 was rotting away so needed replacement & didn't like the price of the genuine system. I did not like the look of the Motad Nexxus system, which had stainless pipes but chrome cans & got the Laser 4 into 1. The quality of the system (full stainless) is very good and the only snags with fitting was that the can bracket needed bending so that the can cleared the swinging arm and the left hand pipe touched the engine mount which was dealt with by massaging with a large hammer
Started it up the weekend and it sounds fine for a street legal exhaust :D I heard after I bought the Laser that there are major fit problems with the Motad system

& that I had made the better choice with the Laser, which was cheaper anyway.
I'll get some pix up sometime.
Also been overhauling the 1100 brakes & needed new brakelines. I found full stainless coloured lines from HEL were far cheaper than anyone else. Had to give them measurements for the front 2 lines (2 from master to calipers to replace the original 3 lines) and clutch line. Colour match was almost exact for the 1100 blue which was a bonus. Not fitted the brake lines yet as I still have to refurbish the calipers.
HEL also do green which is a plus for Kawasaki Ninja owners :cool