The USA Stelvio replaces the very good looking front turn signals with mirror stalk turn signals which make the mirrors nearly useless. The stock signals don't meet some US requirement for surface area or ?
First step, order up the following:
#AP8104921 Right side mirror (standard Aprilia style)
#AP8104922- Left side mirror
#978428- Right side 'Euro' turn signal
#978427- Left side 'Euro' turn signal
I had good luck getting these from MPH in Houston where my dealer has been waiting for months. You are going to be on the hook for about $120 all told.
Take off the wind deflectors, right and left side panels. You are faced with the toughest part of the whole job, push nuts. Seen here with black backing washers.
Take a small screw driver and maybe something to pry the little suckers (carefully) off of the plastic posts. They are not too hard, so the process takes about 15 minutes per panel. You only need the four push nuts to access the hex screw shown above.
Take a large drift punch, socket, or some round stock that fits into the push nut rolled edge, bang the tangs back into place (not done yet in the photo above).
Replace the painted over turn signal with the correct one using the single hex nut that now can be reached.
Use a 1/4" drive, 1/4" socket to push the push nuts back to where they came. Don't forget to put the black backing washers with them. Socket pusher shown below (you can use a small hammer to assist).
New signals in place...much better.
The Aprilia mirrors found on Tuonos, Grisos, and the like do a fine job on the Stelvio. This is what they come with everywhere else in the world. They are also cheap...and don't vibrate at speed.