I think Japspeeds issue is that quality control seems to be down a bit in the priority levels, I'd guess it's because the parts are made for bottom price in China. I know plenty of people who are perfectly happy with Japspeed bits, but other people who have had no end of issues with parts.
It's like anything, you pay your money and you take your choice. If you're happy that you might need to make some adjustments to the exhaust when fitting it then great, crack on. If you want to get something 100% guaranteed to fit, then you need to spend a bit more to be certain.