There arnt many boards for the impulse besides the ones that smartparts make (well none that i have come across or heard about). But the Cricket board seems to be the best, non-vision and vision version n.b. you need an eye installed in your impulse to get the full use of the vision cricket board
As mooney said the only board you can get now is the stock board from that smartparts produce and they have developed the new cricket board and as mooney also said if you dont have vision then dont get the vision board unless you want to upgrade it.
As Skullicious says, turbo (or anything more than semi) is illegal in the UK under the firearms act, i.e. lock you up for months illegal rather than just tournament illegal.
There's a revised version of the cricket board due out any time now. Not sure what the differences between the new one and the current one are other than it's supposed to be more reliable.