Mines is 27 lb1/2 complete with pedals and mudgaurds (but no mud). I have got tubles Hope/Mavic wheels but otherwise standatrd spec for a Pro 2007.

Any tips on what is worth upgrading to make it lighter?

The usual bits, tyres, seatpost, saddle, bars, stem, grips etc. Look at any of the threads about bike weight for more!

Are you ripped and lean? With total bodyfat less that 8%? If not train more and loose some weight, this will have far more of an effect on your riding than a lighter stem or seatpost!

27 1/2 lbs seems pretty damn light to me, although I do find people’s scales seem to vary 😉

Do both?

although I do find people’s scales seem to vary

Hmm – yes, I do seem to have quite pessimistic scales compared to most on here 🙂

That already seems very light for a 5.

Mine is nearer 32lbs, 2007 pro Hope with the following changes:
140 RLC upgrade
Thompson stem
Monkeylite carbon bars
Gravity dropper seat post
Moto V2 brakes with vented rotors
Dr sludge tubes
Wire bead single ply High rollers

Drops to around 30lbs in race trim, Thiompson seat post, standard tubes and Panaracer Razor tyres