gear swapping.. in hindsight id say its a waste of time to split a box purely to swap the cogs but if its in bits you might as well do it.. i ve never used anything other than 1st on the bantam in a section, never been tempted to go for second..
'after market' lower second gears.. again not something i d plump for. many have had issues sometimes even from reputable sources
building a bantam box is not a 5 minute job splitting cases etc. so if i had a built up engine i d leave as is. if it were in bits i d swap the cogs. i wouldnt fit a lower second.
again as for engine mods, my bike is standard b175.. cept for electrix world ignition and a pickering exhaust and silencer.. it runs very very well and is easy and forgiving to ride. certainly the best carbruerrted bike i ve ever owned