Jfsram

First of all. Nobody's speedometer is off by 5 or 10 mph. That would mean the needle is out of position. Not likely.

A speedometer is better described as out by a certain per cent. Like 5%. No matter how much your speedometer is out. It's correct at zero. If you think it's out by 10mph. Double the speed and it's no longer out by 10 mph. I garantee you it's now out by 20mph.

Anyways, that's just nit picking and here is another fact for you.

The 23 tooth driven gear driven by a 8 tooth gear is a self destructing combination. I had 3.73's in my car for 1 year with the advised speedometer gear. After swapping to a set of 3.27 rear gears 25,000km's later. The white 23 tooth came out and it's worn to nothing. Do not recommend this set up.