hmmm, 400hp not cuttin' it
unless he's prepared to own it outright with no warranty of any kind, I suggest he leaves it alone..
if he has a lot of money to burn then by all means, strip it, tune it, roll coal
, etc. however he wants to beat on it..
as far as the current issue, what's the problem taking it to the dealer for warranty repairs?
the fed emissions warranty should be covering that even if he has no other warranties..
his dealer's charging $100s + waiting 3 months for parts for a 2015 model? please share p/n's, that sounds like BS..
good luck to him!