front mount it'll run better because the intake charge will be cooler. hot air rises so the old top mount intercooler is fatally flawed in that all the heat from the engine passes through it.
as a result you'll be able to run higher boost, or more timing, or just overall have a far better car to drive cause its not going to cause troubles when you're driving around with 1,000,000,000,000,000 degree intake temperatures (please note at that temp, you and your car and potentially the rest of existence would have melted)
piping it really depends. you dont want it too small but also not too big. i'm under the impression that 2.25 - 2.5" is a pretty good size in general. if you go too big then your off boost lag becomes more noticeable.. too small and your whole system will be a restriction and generally pointless.
the thing is though, with the off boost lag, if you have a good tuner, they can most likely tune it out for you. one thing i recommend actually.. make sure you have your turbo powered car tuned properly! it makes such a massive difference!
i'm available most weekends lol.. been wanting to visit new zealand.. you pay for flights of course