to give you an idea of my experince of ebay tips..i used a 3.5" burnt tip one around like 45$or sumthn. The exhaust shop guy new instanly the moment he pulled them out of the trunk that they were cheap and told me he dosnt reccommend using these cuz they will blow out.
so,i drove over 500miles with them, the weak SS metal broke around the weld on the hanger leaving a big hole on the side. then also as he said the whole inside of the muffler blew out,so i was left with just a coffee can type deal pretty much.
with my experence,id stay away with cheap parts that get really hot;exhaust,headers.ect..but its your money and ur car.
just telling my experince with ebay tips.