stock or aftermarket
 

Hi I have a 1991 f250 7.3 idi turbo. And I've read in other forums that ats made a stock turbo but welded em up so they won't spool and cremped the exhaust so it was only 3% better than the non turbo. And I was wonderin how can I tell if mine is the jacked up stock one or the aftermarket one, or if what I read is even true? Thanks

If yours is a 91 its not stock.

Alright thanks.