I had a new Turbo installed... And made a discovery

[Unilevers]

honestly, if it was my truck i would force em to put the 551 on there. they screwed it up not you and the 551 is the bigger turbo and can support more power and flow more air safely.

also the charge flow system and cal must match to get peak efficiency - not so much when mandate removed but it still wont be 100% right when mixing turbos.

if you had a 551 on it and you went to a 561 the cal will have to be adjusted.