Go with known brands.. they have been tested by the automotive community, and proven to work. You won't be disapointed.
"Hey bro, what exhaust system is that?"
"Ughh, I dunno I bought it off ebay."
Vs.
"Hey, bro, what exhaust system is that?"
"Running Hytech header, 4-2-1 with a 5Zigen...