Getting the (close to) perfect 8.44 is what you want. Here's how to get it.

My old guide was for sub 20. This one is for the time I bet you can't believe.

First off, you'll want the Sub-Machine Gun. Down near the first batch of Death Leeches, there's 2 weapon crates. Get the guns in both of them. Use up all 40 shots. I'll also say now that if every shot hits, it will take 175 Sub-Machine Gun shots to destroy the tank. You want to dish out 174 shots in 5 lives. Get in the 40 shots and lose a life. If you touched a checkpoint, you're screwed. Continue until you lose a life when the shield is gone. Get in 14 shots next time and lose a life. Next, it's the deciding moment.

You might have known this by now, but I'll tell you in case you didn't know. If you jump and your jump comes in contact with the tank, it does the same amount of damage as one Sub-Machine Gun shot. That's how you want to get the final hit in. On your final life, hold up and at the right time, jump when you're close to the tank. If it is destroyed and it takes one hit, you'll have somewhere around 8.5 probably. If you hear it take damage twice, you missed a shot and you'll probably get 8.75 or something. If you got around 8.5, you want it lower. It might take several tries, but you should eventually find the correct timing for 8.45, but you can go even lower. You got the timing for 8.45, so what if you jumped at a different time? You're gonna have to make an indescribably microscopic change in your jump timing. With a little practice, and a little patience, you'll get 8.44 with ease.