How can i properly mod cars?

[PSPDOGGY]

I know how to mod xbtl files but all of my results are horrible! I would love to make cars like the hammer or quaser really fast and improve their handling but i dont know how. I downloaded these https://www.saintsrowmods.com/forum...st-cars-and-vtols-v1-01-adds-missed-vtols.99/ and they were really good anyone can help me make some cars like this or point me to already modded files? thanks

 

[[V] IdolNinja]

Use winmerge and compare the modded files that you like to the originals to see the changes:
http://winmerge.org/

Then apply the same type of value changes to the vehicles you want to change.