My Cascadia build.

[ricm]

nice build - I like your choice of hop-ups.

spur gears are noisier than helical gear on a like-for-like basis, but because Tamiya uses nylon gears, the orginal spur design will be quieter than the metal helical alternative. I agree with the view that stock ones are good till you break 'em, at which point you can justify the upgrade!