Well I am ready for this upgrade. I want to make sure it fits correctly.

Also if someone knows a part number, and where to buy it for around $60??

Will a 04-06 TL, or what year will it fit my car??

Is it true to go thicher like 20mm, or just 16-18mm??

For all the details, please search the forum as this has been discussed many times before. I'll give you some quick answers though to get you on your way...

17mm vs 20mm:
This has been debated on nearly every forum. I've just purchased mine (17mm), and I'll say why I went with it over the 20mm. Basically with swaybars "bigger isn't always better". There is a formula for working it out (don't remember it), but essentially the values increase exponentially, therefore the 17mm bar is approximately 100 times stiffer than the stock 13mm one, and the 20mm bar is around 50-100 times stiffer than the 17mm bar. If you put too big of a bar on the back ends of our cars (or other front heavy FF cars) and you distabilize the weight of your car in a corner you can end up with something referred to as "snap oversteer", which basically means you will spin out (or worse). The 17mm is less prone to this, therefore imo its a safer option when you can never know what the idiot on the road in front of you is about to do (or not do).

For this one I really do suggest you do a good search, then think about which you truly do want (I know V6Performance has a lot of info on this upgrade as well).

17mm TL Swaybar Part Numbers (what you need to order if you want the 17mm):
Qty 1, 52300-SEP-A03, 17mm Stabilizer Spring (Sway Bar)
Qty 2, 52306-SEP-A02, Stabilizer Bushings (17mm)
Qty 2, 52308-S3M-A00, Holder

19mm TL Swaybar Part Numbers (what you need to order if you want the 20mm):
Qty 1, 52300-SEP-A11, 20mm Stabilizer Spring (Sway Bar)
Qty 2, 52306-SEP-A11, Stabilizer Bushings (20mm)
Qty 2, 52308-S3M-A00, Holder

As for locations to buy, any Acura dealer should be able to source the parts for you (I just got mine at a local dealer near work). You might be able to find better prices online though (unfortunately I don't know any off hand as I live in Canada and Acura/Honda have "no export" laws in place).

I also noticed you said you have a hybrid...I've never heard of anyone doing this to the hybrid, although its the same chasis so there shouldn't be any real issues. The only thing that I would check and make sure you do not have anything that would get in the way (not sure were the battery packs are back there), that might prevent the larger bar from going on properly.

Anyhow I hope some of that helps.