remote start recommendation, G35

I blindly trusted the install shop recommendation for my wife's remote start and while it works, it has issues I'd like to avoid so I thought I'd come here for some advice.

I need a remote start for my 2003 G35, features I'm looking for:
- doesn't eat batteries every month or two
- near instant response when I press the door unlock button (wife's takes 3-4 seconds, very annoying)
- prefer 2 way

I don't care so much about massive range, the car is never more than a couple hundred feet away.

Would be nice if it integrated with the factory remote features (which includes trunk release) but not essential. I can deal with two remotes if necessary.

Thanks for pointing me in the right direction, I appreciate it.

What system did they install? If it offers activation input you may be able to just use the factory remote to activate the starter.

nothing has been installed yet, im asking for recommendations on what to have installed.  the only thing in the car now is just the system that ships with the car from the factory.

The Nissan/Infiniti vehicle's remote control will work when the vehicle is running. You can get a system that does not include remotes like a DEI 561T and use the factory remotes to activate it by pressing lock 2 or 3 times (I recommend the 3 pulse setting). You will need to use either a universal key in a box type bypass (DEI 556U) or a bypasskit.com bypass like the XK07 that does not consume a key. You could also do a system that does control door locks and trunk and will have significantly greater range but these will be cost more.