what will cross over with town car???

i have a 94 lincoln town car............i only want to do 3 things to it........but the most important thing i want to do is the exhaust.........it needs cats at this time...........would the exhaust off of a 96 mustang work????
i also want to change up the air intake set up.........it need more air for sure.........was thinking of drilling holes in the bottom of the air box.........would that work?????
last but least.........computor chip????? found one from jet.......but its for a mark VIII........that speed limiter has to go.......
any imput would be a great help........

thanks ......mom