[thaicbr]

What has an exhaust go to do with 1st gear?,
It wont change the rev limiter lol.

As to gearing it up that would be a big step backwards, go the other way if anything... or.. leave it stock.

By putting a decent exhaust on the CBR250r it makes the engine breath better therefor revving faster and higher (you only need to see the Dyno to see that)

as for 1st gear if the engine is bogging down at a certain revs then curing the bogging will make the bike slightly faster even in 1st gear.