There is a similar thread about modded Gen 5 vs Gen 6 cars
I also agree with others, new 1LE will feel a bit slower since you have a lot of power so on highway pulls or drag racing it will most likely pass the Gen 6 SS. That being said, Gen 6 1LE is slightly faster than Gen 5 Z28 (even without the lighter 19" wheels, Trofeo R tires and those carbon ceramic brakes) at West coast tracks (driven by Randy Pobst).
This is what I posted in the other thread:
My friend's 2014 Camaro 1LE (LS3 with Header, intake and tune) vs my 2017 Camaro SS 1LE (bone stock LT1 engine) Same dyno, different days but very similar conditions:
Cars are identical up top but the low end torque advantage of the 1LE is very apparent
