what's the best one these days?

 

The cheapest is the standard ignition key. Just don't
turn it off till the car has idled in neutral for a minute
or two. I do. However, there are simple cheap units out
there that promise to keep the car running for a time
after you've removed the key... That would be cool,
but I haven't heard anyone yet who has installed
one on a 996tt. Let's see who else posts...

 

I did have one installed for a long time on my car. The Apexi... but you should know it's NOT as easy to install as on Japanese cars that have pre-made and cut wiring harnesses. You have to do some cutting, finding etc.. and it's not even worth it since you can't turn the alarm on until the car shuts down. So in other words you wait for your turbo timer to shut the car down from the outside and then turn the alarm on.. Not worth it