I find most of these issues are when modifying files like the default.ide and handling.cfg ect.
Some new mods have the text setup differently so you have to compare the original values and the new ones and fill in the gaps. I have enough cars where it will actually be too obvious that a mod is present. The game will get extremely choppy (but those new cars look so damn good!)
aside from all this I haven't had any problems with the "greetings from vice city" screen. Still lasts about a half second or so.