just been on ktec racing site and there developing a catalytic convertor replacement,,not a decat,so you dont need to put your old one back on at mot time,will pass emission tests etc ,due out in mid july for mk2 172,then version for mk1 172 hmmmmm sounds good about £250.
if it stops my 4k buzz and gives 6-8 bhp increase may be worth it!!? cheaper than a renault original?