Put majestic.dFF, majestic.tXD and majestic1.tXD ... majestic5.tXD in a folder inside of your modloader folder or remplace the files in your gta3.img...
Remplace the lines in handling.cfg, vehicles.ide, carcols.dat and carmods.dat respectively:

Handling:
MAJESTIC      900.0    1600.0   2.2    0.0 0.0  0.0  75  0.65 0.90 0.50 	5 140.0 25.0 10.0 R P 	7.0   0.52 0 35.0  	1.2  0.10  0.0   0.31 -0.15 0.5  0.3		0.47 0.40 70000 	2000 		430001 	1  1 	1

Vehicles line:
517, 	majestic, 	majestic, 	car, 		MAJESTIC, 	MAJESTC, 	null,	normal,	8, 	0,	0,		-1, 0.62, 0.62,		0

Colors line (delete the original majestic colors line and put this line in the "car4" session):
majestic, 1,0,1,0, 126,126,126,0, 3,3,21,0, 80,25,80,0 125,125,36,0

Carmods line:
majestic, bnt_b_sc_m, bnt_b_sc_l, bntl_b_ov, bntl_b_sq, rf_b_sc_r, exh_b_m, exh_b_l, lgt_b_rspt, lgt_b_sspt, nto_b_s, nto_b_l, nto_b_tw, spl_b_bar_m, spl_b_bbb_m, wg_l_b_ssk

Now open cargrp.dat and put "majestic" in these sessions, this is important if you want to see The Families, Vagos, San Fierro Rifa and Aztecas driving his own car version:
# Gang 2 (FAMILIES - PLAYER - BLACK)
# Gang 3 (LSV - MEX)
# Gang 4 (SFR - MEX) 
# Gang 8 (VLA - MEX)

-IonicCleric8076-