injector size and tuning?
 

i just put a new motor in my car because i blew my last one with nitrous, I upgraded the injectors to 24lbs, not a big increase but now my friend is telling me i need a new mass air. i was under the impression a dyno tune would do it but he says no. i know a lighting mass is required with the 42lbs injectors but i only upgraded to 24.

What other mods do you have?

Depends on the year of the car, if its a 96-later you dont need a maf just a tune.

its a 99 gt 5 speed, has bbk lt's, o/r h pipe with flowmasters. under drive pullies, mach one intake system (doesnt do anything) with a k&n air filter, 3.73 gears and putting back the zex kit with a 100 shot.

You should be fine with the stock mass air...

You dont even need bigger injectors assuming its a wet kit.

I did it
 

I just done mine last week, I have a 2004 mustang gt I installed 24 lb injectors and had it tuned, there was no need for a new Mass air

you only change the MAF if you're pegging it or it's broken. 24's are fine if you like nitrous that much. Lightning MAF's aren't required with 42's. A proper tune adjustment is required after a change in injector flow rate.