8 hour stopover ain't much considering the fact that your transportation time to and from Kowloon will take 2 hours away from your 8 hour stopover. Additionally you will need another 2 hours for your check in when you leave HK and 8 minus 4 and you'll have max 4 hours left. Factor in another hour for traffic jams and walking time, you are now left with a mere 3 hours.
If I had only 3 hours, I will visit Mongkok/TST instead. Plentiful of eateries and shopping there.

Aiyah, 1 hour to Kowloon and 1 hour back = 2 hours lah. You are not thinking of calculating only a one way trip, right? I am estimating by taxi, not express train. Also, you better pray that their luggage handlers aren't on strike.

Bro, food in Kowloon is aplentiful. All yummy. What you have to do is just walk around and see which one is crowded with a queue at the front. That's the one you should try lah. What time are you landing in HK?