Yeah the alarm retrofit is really easy for the convertible since its basically just a hood switch and the siren in that wheel well. For coupes and sedans there is also an ultrasonic sensor in the rear(?) overhead cabin light. There was a very short window where the alarm was optional and also prewired, ended with early build 2009 cars I believe. I did a write up here:
https://bmw.spoolstreet.com/threads/e93-alarm-retrofit.1445/
I love having the accoustic beeps. No more wondering if my car locked or not.
I read this, very interesting.
Also,
UPDATE:
So I decided to change the sparkplugs w/ the proper Bosch ZGR6STE2 ones.
When I pulled the coils I saw that the sparkplugs in place were not 12-point, but NGK PLZKAR6A-11 hex plugs [usually used on nissan sentras? LOL]...so I automatically knew I had to find my funderwear because this was going to be a fun day.
For some reason I just couldn't find a socket to grab and undo these plugs so I bought a bunch [I have a stack of sockets I have to return tomorrow to Autozone] but they did have a 14mm 12-point thinwall sparkplug socket w/ rubber insert for like $6.99 or so [I removed the rubber insert otherwise it was glued to the plug]. As I was trying to remove the plug from cylinder #1 I noticed the coil couldn't be pushed completely down and when I removed the coil I saw that the sparkplug was loose. My heart dropped a little.
Sure enough, one of the threads in the head
seemed to be cross threaded or something. Back to autozone to see if they have helicoil for 12x1.25...they obviously didn't. Got home and ordered the Time-Serts sparkplug kit from Amazon along w/ 22mm inserts.
I then went back outside and decided to inspect the other 5 plugs and change them, which went smooth. Then I got an idea: I took my drill and with an adapter I put it on the slowest speed and attempted to tighten the plug while pushing on it gently and holding the drill very still. It spun a little aimlessly but it ended up catching on the threads!! Once it caught a little I hand-tightened it accordingly [17ftlbs according to the box the plugs came in] and went out for a test drive.
No more sputtering, stuttering, misfires, etc etc. Car runs smooth at WOT throughout the rev-range. I would like to take a moment now and thank Jesus for not letting this become an expense in the thousands
Also, the clown who previously owned the car...