If the MTX-4 springs are the same as the ones for the MTX-3, than this is the table

Mugen MTX – 3 Springs

Purple - 1.6mm
Light Blue - 1.7mm
Dark Blue - 1.8mm

Purple front springs= 25lbs
Purple rear springs= 21lbs

Light blue fronts springs= 31lbs
Light blue rear springs= 27lbs

Dark Blue front springs= 32lbs
Dark blue rear springs= 27lbs

All measurements were taken using the Xipp spring dyno.
And the tenths, hundreths, and thousanths were all rounded off to nearest denomination.

AFM