Picture below

For some track days and some road use I wanted to be able to quiet them down.
I have found two options and need some help
http://www.motorbikepartsdirect.co.uk/p ... e-kit/576/ £9.98
or these
http://www.motorbikepartsdirect.co.uk/p ... iller/640/ £29.98
Any one used either?
I'm confused as to the big price difference and what effect they would have.
Any help appreciated.
styler