How do you fit them? do they glue on? or is it worth buying a performance bonnet with ready cut vents ?

Don't do it

clicky the linky : Cool Louvres :: Release the heat

Louvres are very cool. very euro

im liking that cool louver site, im thinking about getting them "Bad boys" ;) hehe

Yeah, I've seen Stilo's with bonnet vents and most of them look a little iffy in my opinion. I'd say if you had to do it, something like the old Astra GSi vents or something similarly subtle would be best. But as Dan's brought up, it could be iffy in terms of the electrics if you get the placement of them wrong and the stick on ones do indeed more often than not look horrendous.

i had a 206 1.9d with a 1.9 d turbo transplant.
it had a full ecoss bodykit and an F50 bonnet vent, TBH i'll never have another car with a modified bonnet. it weighed a tonne and the bonnet had to be redone 3 times because the filler & fibreglass cracked.
it was showing signs of cracking when i sold it, i only had the car 6months.
NEVER AGAIN!

bad pic but you get the idea

i dont want anthing massive, just 2 small vents in the middle of the bonnet further to the front of the car, just to stand out a bit

That does kinda look nice........Cost though is it worth it