For the street, i`d recomend a single turbo off a twin turbo skyline. The genuine units have a ceramic turbine wheel that limits them to about 12Psi. They have an exhaust AR of .48 and will make over 100Kw ATW on a good engine.

If the budget allows, buy a new replacement one from garrett.$1130, These are a BB unit and rated at around 250Hp. It will make good power from 3500rpm on an A14.707160-7 is the part number from memory. the 707160-5(GT2860 w.64 AR exh) is the upgrade turbo that i have on my A12 but it doesn`t get really cracking till 5000rpm. It would come on a little earlier on an A14 but probably too large for the street. It is rated at 350Hp.

Check the Garrett website to see the all the specs on these turbos.