The gezzer at motorworld told me not to get the twin 5 inch universal one, especially on smaller engine cars, because it is not built for your car and can make you car perform crap. The 5 inch tailpipe makes you loose quite a lot of power, smaller tailpipes will perform better he said.
I know what he means though because when I had me standard zorst on the power was instant as soon as I put my foot down, now I have a crap peco powermaster which sounds nice except it defiantly has made me car a bit slower, when I put my foot down it doesn’t seem to respond as quickly as it used to.