The aftermarket stuff may not be a safety concern, but they can be a legal concern. WHen I bought my SV650s, the person who had it before me had replaced the undertail (and turn signals) with a Hot Bodies kit. That made the rear turn signals into little 4-LED things underneath the fairing that were virtually invisible during daylight. I added some other, much larger LED strips which I glued to the outside of the rear fairing. MUCH better. I then added similar strips on the front (kind of like eyebrows over the headlights). The bike also had flushmount front signals…
Well, I had a contact by a state trooper on a ride… Funny thing was I wasn’t even moving at the time — I was stopped on the side of the road to take a Mt Dew slash before turning around and heading home. He was cool about it when I told him the history of the bike, saying that since I’d made an attempt to make the signals more visible he wasn’t going to write me up. But he also ran down the list of why all my signals were illegal.
Now this applies in Washington, and MAY apply in your state, as it’s a federal standard (states often just defer to the federal standard):
Turn signal lights must be 3.5 sqare inches in area (equals a 2″ diameter circle approximately).
Rear turn signals must be separated by 9″. Can be red or amber.
Front turn signals must be separated by 16″. Must be amber. Must be separated from headlights by at least 4″.
So I went to a lot of work to redo my fender eliminator, and installed stock signals in the rear (still have the LED strips active, but they’re strictly not legal and COULD get me written up, even though I have the stock signals working), and I installed stalk-type (though not original stock) signals in front.
So maybe that will help you out.