It won't increase the power of your jets, but I recommend some non-return valves from Halfords 
I always thought that would help, but i've tried it and it didnt help! Might have been a cheapo valve, but it did come from a Volvo...
how did you make them heated chap?
Are mk2 jets heated allready?
how did you connect the 2 extra jets just with like T pieces? diddnt that make them have less spray power?
lol sorry chap, questions questions. 
They come heated as said from GTI's or MK3 golfs, in fact, not sure if oter models other than GTI's came with them probably GL's as well, someone will clarify..?
As for connecting them, they slot in the vent, with a little silicone (which can be removed if you change your mind) then you just get some extra hose and plug in the t-pieces
