Ive been running the ASI 56mm in my 300zx for nearly 2 years, not even 1 issue yet. I also ran it in my drift r32 but i could not fit the shroud and the fan ended up eating the radiator to bits after 1 track day but it did keep it self fairley cool before it got eaten.
Oh and as for there service i found it pretty good. I had an issue with the post company, I had the rad delivered to a mates house, he was on holiday and the time so they left a card, i got the card and went to try pick up the rad and they wouldent let me as it had my mates name on the box, i ended up ringing ASI and explaining the situation, asi then rang the shipping company and faxed over proof of payment ( from my bank account ) and gave them all the required info. bit of a head f**k but they helped me sort it all out!