I emailed my friend for that info. he's out of town so he might not reply back promptly. however I've had others who had their audio systems installed from 6th ave and they surely did a good job with the audio. the alarm. well can't tell u since i dont know any who got it from them. do ask for their installation prices though. at times they're a tad bit towards the expensive side. however if you're considering all those gadgets and leaning towards the more expensive 550 viper then i would suggest you also take a ride down to "Lee electronics". he's off of route 1 south bound right after the open road bmw show room. he quoted me $300 for the avistart system, also by DEI. he does have others. he charges a bit more but he seemed to know a whole lot more than the best buy/ circuit city installers. more over I don't think the trunk opener would work with the benz since it doesnt pop up like the japanses cars would that have a trunk open button inside the car. so even though you might get that added feature with the remote u might not be able to use it. however if you're trying to get more gadgets then try to get the optional components for the power windows installed. u will get the added benefit of one touch up/down of the windows from ur center console with that option, more over you can drop/raise all ur windows through ur remote as well. but u're looking at atleast spending another good $150 on top of the basic installation for this.
Don't let the tech cheat you into getting extra relays for the vaccum locks. if the installer really knows the benz then he should be able to tap into the existing switch and by pass all the relay BS that so many talk about. also, some shops force you to get a mercury fail safe switch installed under ur hood. with ur benz you already have that switch installed, not mercury however but nonetheless, and that switch should be used with the remote start. also, best buy forces customers to buy their 10-guage wire going from the battery to the alarm. well if the benz has it's own wiring sufficient to start the car then what's the need of an extra positive wire all the way to the alarm, where as all the other connections are still being tapped into the existing cirtuitry. just another $35 to $40 they charge which basically makes the shop money off of it.
they are just things that i've seen people being charged for sometimes upto $150 because the owners just arent aware of it and the shops like to make money off them.
good luck !