I am not sure what "...not under city of Katy Limit." means, but you are dealing with a fair bit of power here, and you do not want to see your house go up in flames here to save a couple of bucks on permits, or a sub-standard installation. Get somebody who has done Tesla chargers before.
Katy has the following - "The City of Katy is a Zoned City, and we do require permits to be obtained from the building department BEFORE work is started. Permits are required for... electrical...", so yea - you need one
and
EFFECTIVE JANUARY 1, 2019: The City of Katy has adopted the 2015 International Building Codes and the 2017 National Electrical Code.
Permits & Building | City of Katy, TX
There are tons of entries in this TMC on charging installation. the good, the bad, and the Ugly.
I am in Fort Worth. I had requested 72 Amp capability, as I had the available current capability. During the install the installer could not find a 90 Amp breaker, so put in an 80 amp breaker, and then set the HPWC to 60 Amp Max.
During my initial inspection, (the installer was not present-nor was required to be) the inspector wanted to verify the current limitation of the HPWC setting, when they could not get the cover off, the deferred the inspection until the installer could come out to take off the covers for that verification. The Inspector was very clear that their task was to make very sure the installation was correct so that there was no safety issue. Since it was my house, I absolutely agreed with them. The second inspection was very quick.
Eventually the installer was able to get the correct 90 Amp breaker, and reset the unit to the full 72 charging capability.
I normally just plug the car in at night and it is all charged put in the morning for running around. In the year and a half I have owned the only once have I really needed the high speed charging capabilities mid-day - so in my case - having the 72 Amp capability is really overkill.