The only eBay chip I've had anything to do with was on a Mk4 Tdi on the most recent RR day at Carbon Chiptuning. Car should have been 115bhp standard and was actually around 135bhp and had very nice power/torque curves. It did however leave a big sooty mark on the floor and filled the garage with black smoke
There are 2 choices on eBay. If you just put 'golf mk3 chip' in the search it will come up with em. I don't have one so can't be held responsible if it all goes Pete tong, but from what I have heard, they are not the devil as some suggest.