INSTALL:  USE IMG TOOL 2.0 AND OPEN GTA3.IMG(its in the models folder of ur gta sa game directory)
press f2 and search for mesa  now replace the existing dff and txd with the newer ones that come with this mod similarly open vehicles.ide and find mesa and replace it with line given in this readme then replace the handling.cfg and carcols.dat lines

 
Handling.cfg
MESA 1600.0 3550.0 2.0 0.0 0.0 -0.55 70 0.90 0.8 0.52 5 535 58 25.0 R P 8.6 0.67 1 38.0 1.0 0.12 0.0 0.34 -0.08 0.39 0 0.26 0.54 150000 0 10000006 0 3 0

Carcols.dat
mesa, 0,0, 1,1, 3,3, 4,4, 24,24, 41,41, 53,53, 75,75, 91,91

Carmods.dat
mesa, lgt_b_rspt, lgt_b_sspt, nto_b_tw

vehicles.ide
500,	mesa, 		mesa, 		car, 		MESA,	 	MESAA, 		null,	normal, 	8,	0,	0,		-1, 0.77, 0.77,		0
  
 Hope u enjoyed it