Until you do something to change the power the engine is capable of producing, putting in larger injectors is a waste of money, a waste of tune, and will decrease the fuel efficiency of the engine.
I took my 2000 LS1/4L60E and installed an LS6 cam and intake, and 317 heads shaved to LS1 chamber size. Long tube headers, free flowing exhaust and air inlet. With higher stall and taller gears and the 28 lb injectors that came with the LS6 intake, it pushed a 3400 lb car to 11.95's @ 114 MPH in the quarter. While I didn't datalog, it showed no hint of needing more fuel flow.
IIRC, stock is 26-28lb depending on the year. Not much of a gain for the $. I ran the stock 28lb cam only. All they'll do for a stock engine is require a tune to run at a lower duty cycle. In essence you'll spend the $ on larger injectors so they'll deliver the same fuel charge of your stock injectors.
I ran SVO 30# injectors (they run 36# in LS's) in a 408. It was still running the stock fuel pump too.
Oh, and forget about superchip and any other hand held "tuner." When the time comes for a tune get a dyno tune, or the software (hptuner or ls1 edit) and learn to tune it yourself. Be careful with the last option, you can lose your engine from a bad tune.
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