The F1 Stealth is a 'race mod' version of the F1, so no you cant make them the same as the Stealth is a proper race car with front aero and more rear aero, stock it has the customisable trans, suspension, drivetrain parts, etc.
You now have to buy them from ebay (originally came with pre-order and special editions).
IMHO the McLaren is the weakest of the stealths when compared to the original car. The standard F1 (suited and booted) is lighter and more powerful and also has more pp. On a power track like the High Speed Ring it’s about 1 second faster and only 1-2 seconds slower on Trial Mountain. The stealth is much, much more enjoyable to drive though. It feels lighter (even though it’s not) and is much more forgiving and less skittish. Trying to copy the setup only makes the standard F1 more annoying to drive and with identical suspension and max downforce the normal F1 is actually slower than with the default setup. The other stealths all seem to be noticeably better and have more pp than there equivalent models… even when fully modded.
The BMW F1 GTR comfortably beats them both… I wish they had stealthed that one instead.
If you want a stealth then buy the 787b… probably my favourite car in the game.
hawkeye122Edit: Wow, now I feel stupid... Are you talking about the McLaren F1, that is sold as a BMW?
I haven't checked this yet but the F1 Stealth may have an adjustable front wing and higher overall downforce than the regular road car can ever have, which would explain the Stealth's more forgiving handling.