I have a 1990 Max and wanted to know if i decided to switch my 125 mph gauge to the 145 guages what exactly would I have to do in order to keep my speedo readings accurate.

 

yes, works perfect.
all you need to do is get the 145mph speedo and swap it in. the only problem would be you have a gxe, and since gxe's have the black gauges, if you only swapped the speedo you would have a mismatched gauge. so you might as well just buy the whole gauge cluster and swap it over, and just dont forget your redline is 6000rpm and not 6500ish rpm.

for more details you can search both maxima.org, and the forums at max-world.org, I've done writeups on both sites with pictures covering the conversion.

 

i will do that