Question about gauges

how can you make your speedo read more and be accureat i.e. going from a 120 speedo to a 160 speedo

That would just give it a bigger range, but I doubt your car can do more than 110 anyway. And a bigger range isn't going to matter if your car can't even use most of it. The only real way would be to replace the sensors and measure speed but I don't know if ant aftermarket ones that would be better.

it was just an idea of mine.