alot of ebay turbo backs ive dealt with have to be used as an entire unit, cant be seperate and used as just the downpipe or just the catback as they have there own, non-oem lengths for some reason. i had an issue years ago with this as the guy i bought the catback from bought it as an entire turboback and installed it as a turboback so when i bought the catback he was unaware there was going to be any issues.