grs fit very very well (mine does neways)
and its shifs well enuff till i turn the boost up more
uni cooelr will be fine aslong as
1,its gonna fit (not just the placing but hose work, fans in the way etc etc)
2, its actually better, u wanna have similar bore pipe for ease of fitting and fairly slim to fit in front of the rad cos there aint really newhere else to put it on a rst
they come up on ebay fairly regular