The other question is,
"Does the police or anyone regularly fly around in helicopters" as their FLIR will see a VERY nice hot patch which will have them interested.
And, depending on your utility company, a sudden increase in use at a rate in excess of 3kw per hour may get them suspicious, not so much about you growing but running a business whilst paying "domestic" tariffs.
I know both of these have happened in the UK, and since I don't have a clue about where you are then I have no idea what sort of policies they have at your neck of the woods.
And, as has been said by Capt. Trips, make sure your wiring can handle it. At 230v you will need to be looking at a power supply that can handle at least 20A for safety reasons, always have an excess, never load things to the maximum the breaker says, if it's only a 15A supply then you WILL need to upgrade. On 110v you'll need at least a 40-45A supply as the lamps themselves will be pulling 27A, not including ballasts, and obviously not including extractor fans, airco, and so on. You can always make excuses as to why you need such an upgrade, say your starting to teach yourself machine shop stuff like metal munching or welding and nobody will be any the wiser.
Also, as El Capitano mentions above, if your garage door doesn't "seal", you will likely have issues with smell "leaking" as if you are running that level of lighting you're not doing one or two plants and that is going to be a lot of pong. You MUST ensure that doors, windows, and so on are sealed, if it's a wooden garage then you'll need to check over the whole damned thing for leaks or build a suitable tent inside. Heat will be an issue, so you will need some serious cooling and extraction, and that will have to be noiseless or your neighbours will be wondering why there's the sound of a turbine engine whining coming from your garage.
Plenty ways this can go south, so please remember the most important thing called the "Six P's"
Proper Planning Prevents Piss Poor Performance
Get everything down on paper, get advice from your local grow shop (if you have one) or list some serious details regarding the size of the garage, the construction of the garage, your ideas, etc, here and you can be sure people here will give you the absolute best advice you can have.
This sounds like you're well and truly trying to win the 100m against Usain Bolt before you can walk, you're biting off WAY more than you can chew. By my reckoning this will get VERY expensive VERY quickly so be aware of that. You can't just throw 3Kw of lighting in and hope for the best, you're going to be doing what many would call a "commercial" grow and, depending on where you are, one little mistake could mean you spend some time being VERY careful about how you pick up the soap.
Don't just "do". Think it through, plan properly and execute the plan to the letter irrespective of the cost as shortcuts will be highly likely to you losing everything, whether that is by your garage going on fire or someone finding out what you are doing.
Or scale back a bit, or use LED instead of HID lamps as that will negate some of the heat and power consumption issues.