]
where did you get that from? the chinguard stops Loads of roost you can get your hea down if it s arall rocky section but thats not why the visor is there, you can't look down the whole time.
 A solid mouth piec eos good for downhill anyway when you land on/in piles of wood or sharp rocks if you had a heavily perforated one bits could get through and cut you, also if there were laods of gaps theyw ouldn;t e able to take hard crashes, some of the older troy lee's already had a problem with them falling off!
 

I'm breathing my own air in my 661
i thinks  its time for a new lid 
but come on the average DH run about 4 Min's (where i live)
its simple take your lid of at the end of the run !
learn to control your breathing ... pros do

Haha "steve peat does a skid" thread made me laugh

the chin guard is designed to stop you smashing your face on a bunch of rocks, and has to be relatively "solid" to fufill this function

the more holes you put in the chin guard, the less protection it is going to give your face, as it will flex more under impact 

MTB chin guards actually feel quite a bit softer than those on proper MX helmets where riding speeds and impacts are generally higher, road motorbike helmets have even stiffer chin guards (with less ventilation) as falling onto tarmac can be very nasty at speed

like with the helmet shell itself, its a trade off between ventilation and protection, with more holes costing more money in terms of design / engineering, testing and production of the helmet, as you have to use stronger and more expensive materials (i.e. composites) to achieve this goal

are you actually breathing your own air when your riding as remeber there is air being forced in then

i dont really care about the ventilation in a helmet.......................

when i say i dont care i mean that i would like a little bit of fresh air but

breathing in your own air is a great sacrifice for having your head protected

however some helmets do have big air holes,like these



i think these helmets r quite good 4 ventilation

I can quite happily push up tracks wearing my D2 most of the time and I can't say I've ever noticed the air being stale, personally I don't think it's happening to you and certainly not in a performance affecting way. Are you sure you aren't just unfit?

Have you ever seen someone crash in a full face lid and still smash their teeth out? No? There's a reason for those chin guards...(lid was a 661, the chin guard snapped off.)

Orge.