I bought my HFS-3 direct from the UK, except for the initial backorder wait, it was a completely painless process.
@BlwnAway Howerton had a nice looking tank but don't sale it anymore. What tank did you use? @Dave.0 do you have the Howerton tank ?
I used a 2.25 gal Devils Own tank I found on e-bay Oh... And the pump mounted right to it, no modification at all.
You'll never regret growing old with your R53 .... Well you might have regrets about growing old but having a trusty rock solid R53 won't be one of them.
Mod your MINIs any way you like, but, the ONLY way you can really mod ANY car is to get some seat time at the track. Then, and only then can you determine what your car can do for you with the mods, AND what you can do as you drive them.