Best way to make connection for a Remote start

What is the best way to make the connections under the dash when adding a remote start to a new car?

I know of 2 ways, Soldering (Probably the best but maybe not practical?) , And wire taps?

What do most profesional install shops use when someone brings in there new car to get a remote start added?

Solder all the way.... what's not practical about solder ?? Takes about 2- 3 minutes to find the wire, strip back the insulation, attach the wire and solder and then wrap with electrical tape. This is a professional opinion but you may want to use T-taps to save time, but what else do you really have to do ?? It's not like there's another 3 vehicles waiting for you to install more remote starter's into ? If it's a customer's vehicle...take the time to solder and do the connections right because in the end a returned vehicle with a loose T-tap will cost you more time and money to find and fix, than the time it takes you to do a proper connection the first time around.

If it's your own vehicle...take all the time in the world. It's not going anywhere and if you know that the system won't be in the vehicle too long, use T-taps for easy of removal.

There I said it and I will take any hits from anyone who wants to argue the fact... but remember this is only an opinion... NOT THE LAW !