canned tune is a pre set log of settings thats is known to work in your year car. every car is a bit different that being said a in car tune is always best so its tailored to your car.

theres not a whole lot they can do to pep up a stock engine, but gm did set them up on the weak side and left some power off.

he can also change the trans settings for quicker firmer shifts.

or he could do nothing but delete that code from coming back ever. and call it a day. you dont "have" to get a tune.