LT1 vs S4
#2
From a dig, he has the traction advantage. He should be able to get out on you if you're on street tires. If his car is running well, he could hold you off for a full 1320. If he bogs the launch, he's a dead man. You should take him out.
From a roll, it's a toss up. I've beat LT1s with your mods when my S4 was stock back in 2000. Not by a lot, but I was ahead. My car was a strong car from the factory though.
If it's hot out, you should get him as heatsoak slows us down a little. Just make sure you have good tire and stick the launch. If so, it should be good run. I'm assuming you and the S4 are in good running order.