honestly, its going to vary alot dealer to dealer. i've worked for two dealers personally.
if you walk in with a chip on your shoulder and give the service writer or technician a hard time, you are asking for them to make an example of you. they'll get on the horn to tech line and black flag your car so fast you won't know what to do with yourself.
now, if you go in, be up front and honest and just generally courteous, your service writer and tech will probably take care of you. simple things like intakes, exhausts, shifters, gauges aren't going to get you flagged.
we had a guy come into a local dealer with a full turboback exhaust on his ms6, timeslips on the seat and a boost controller installed. his diff was shot. he proceeded to act like a total screwbag to the service manager so they had no problem flagging his car and sacking him with a several thousand dollar repair bill. on the flipside of things, we had a guy come with an STi who had his engine in - literally - a thousand pieces. the PCM recorded his last 45 minutes of drive time showing him holding at 130 mph or so for most of it. he was extremely honest, generally understanding but most of all polite. he got a new engine for nothing.
as for the legal argument, the liklihood of being able to challenge it, win it and not have to pay the fees involved in doing so isn't that hot. my advice is to avoid that kind of confrontation to begin with by just not being a jerk.
