Tires?...16 or 17

[Rocket 99GT]

I bought new tires, I just to have 245x17 but after lowering the car and installing new shocks-struts my mechanic adviced me to buy 245x16.
He said that the car will be seating even lower (better handling) and he said that with the 3:73 the take off woul be a lot faster with this small tires.
What do you guys think, is he fill of sh#$%^.
Nevertheless, I am happy with the new tires, they Excellent in the rain and snow.
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99GT…..rear sway bar (adjustable), rear lower control arm, traction bars, tokiko struts illumina 5 position, tokiko shocks, strut tower brace, caster camber plates, racing lower springs, 3:73, underdrive pulleys, Michelin “pilot XGT-Z4. NOW I WILL ADD POWER.