Is there really a big difference between the two ?

 

Aftermarket p72 ecu?...no such thing.

 

Oh my bad . I meant like chipped p72

 

A chipped ecu will be tuned for your specific mods, whether done on the street or on a dyno. Using someone else's tune does nothing for you except potentially doing damage to the engine.

Those universal chips you see all over eBay are crap.

Start reading: http://phearable.net/information/efi...ner-guide.html