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I have 35 pound ones in my truck..and they suck!!!
go for the 50 pound ones..better to have more than less...and also..I dont use the poppers itself...the ones that push the door outside...cause you never know and may hit a car on the side or so...the power of the thing itself its enough to pull the door by yourself.
If you dont put the emergency opener...I'll say go for the alarm module that opens the window totally...bad for winter days but safe against thieves...they all know where to look for the emergency button..!

Dont know who's installing them..so dont know about upgrading them..but go for 50 pounds...

Dont think you can use the stock remote.
Get an alarm that has more than 4 functions...like a top of the line one from whoever.....I have Ungo from Clarion and love it..others will say so from Clifford/Viper, and all others, any good alarm and the modules that open/close things will make the job.

GOOD LUCK... and get a good installer to mess around with your electrical stuff!!!
enjoy..they are fun to have and use