mate , the way I see it is that the diffusers are way closer to the globes than anything else, once removed there is more room in there than standard, dont see how you can get more heat from the same globes with or without them fitted!........I had a 66 coupe and the dash lights were woefull, when I built my new car I stripped the dash apart and set the speedo at zero, whilst reassembling it I opted to leave out the little plastic coloured lenses..............what a difference, they were two worlds apart,