i,m unsure of the size of the vxr one but 100% the diesel veccy c air intake is hugely bigger than my standard gsi,the one i had was off a sri model
i,m quite sure it has made a slight difference,im waiting till i can afford more mods like the fmic at least till i go for a remap/and now cat back exhaust
hardly use it at the moment tbh..got a 1.7dti astra estate to toodle about in as its too damn expensive too run lol