How easy is it to upgrade an alarm

Hi, I was thinking of getting a entry level remote entry alarm now (one of the DEI persuasion) and having it installed by a professional. In the future, I would like to upgrade the alarm so it has two way support. I probably won't be adding any additional modules, such as remote start, window rollup etc. I pretty much am waiting for a better 2 way system, but I'd like to get an alarm now. Is it fair to say that the wiring diagrams on most alarm brains will be the same? That they will all be needing the same electrical signals etc? So basically I'm thinking that when I want to upgrade, all I would have to do is remove the old brain, and wire in a new one, re-routing the appropriate wires according? Thanks in advance for any replies!

You can take a good guess to say that if you stick with the same manufacturer within a few years, it may be less work to upgrade from one system to another. As I say though it is only a guess because different models - especially 2 way systems, often use a different main harness, antenna and other connections.

Thanks for your reply csorb. Yeah, I figured that the chances that the harness's stayed the same was minute, but given the wiring diagrams of the both units, does it makes sense to assume one could just splice a new alarm into the wiring of the old alarm? The reason I say this is because I think getting the wiring into the car right is the hard stuff, with the soldering requirements and getting too all the different parts of the car... Anyway, I could be wrong, but I'm just guessing here as well!

If you wish to have 2 way notification this must be purchased at the start. You cannot add two way communication to a one way alarm system. It doesnt work that way. Regards EVIL Teken . . .

Actually, I was told 2-way can be achieved as well through a seperate pager module. This is somewhat more old school. But the benifits of ESP2 were unkown to me untill then. I am looking at getting a 660XP so it has an ESP2 interface. That was useful information. So perhaps the upgrade path will not require swapping out an entire brain... Still, I wondered how it would be done at an install shop..

Where can such units be bought? I surfed around for a bit, and I didn't find much. Are you referring to this sort of thing?

Or an actual responder keyfob? Thanks :)

Thanks for your reply. I got a Phython 660XP installed. Seems to be working fine, (execept the bypass is weirdo, somehow I managed to set off the alarm by shutting the door). I'll keep an eye out for those upgrades in the future.