We'll I recently bought a 3inch cobra exhaust system in august this year for my astra coupe which up until a month ago has been good as gold.
Untill I took my car for a very sprited run to mc donlands and returned home to find the exhaust rattling which i initally thought was a loose exhaust clamp/ heat sheild but after inspection it was definately the CAT's insides had come loose .
So i called exhausts uk to which they were very helpfull and said bring it in straight away or posts the section back for replacement.
I brought it in, there aftersales customer services was top notch unlike a few companys i've delt with, they just changed the cat no quibbles.
Fingers crossed this one lasts a little longer though.