GtStangFGCU

I was just pondering as I am getting ready to make a purchase or two for my blue bomber...When is it appropriate to do a tune for mods (I already know a tune is required for the intake)...but what about cat back exhaust, headers, etc...Obviously you would make more power if the tune was tweaked to aid the mods...but are they a necessity?

ski

Typically, a tune(either a canned one from a supplier, or a custom one done at a dyno shop) is required when an aftermarket air intake is installed.
Afterwards, the tune normally has to be modified if any further mods are done that significantly increase the air flow thru the engine, e.g., long tube headers, off road X or H pipe(no cats), porting and polishing the heads, supercharging, etc.
On the other hand, the tune normally does not have to be modified for any mods that do not greatly increase the air flow thru the engine, e.g., underdrive pulleys, larger throttle body, shorty headers, aftermarket catted X or H pipe, aftermarket catback or axleback exhaust, etc.

Andys06GT

okay, adding the cai obviously changes airflow, hence changin air/fuel ration. throttle bodies, exhaust, etc all change the characteristics of the air flowing to / from the engine. the only way to see the air/fuel leaning or richening would be to put her on the dyno and tune from there. there's no way to do a user adjustment after installing a throttle body without seeing the numbers through a computer (dyno). you wont necessarily NEED to do a tune with those smaller upgrades. but to find the maximum performance and really get yer moneys worth, its a good idea.