Has anybody done this. A buddy told me about this horns called hella horns that are supposed to be louder. Sound kinda cool might be able to really get someone to get out of the way. They see prett cheap to under 50 for the pair.

 

I never put them on my IS because I think the horn is pretty loud but I installed them on my modded Mazdaspeed3 because the horn was so wimpy. They used to be made in Germany but are made in Turkey now but the quality is still good. They are pretty loud. They'll definitely get someone's attention if you honk at them They have a decidedly European sound. If you heard them you would definitely think a VW bus or some kind of Euro car was honking it's horn. A Euro sounding horn coming from a Japanese car is a little weird but YMMV. Honestly I think most people install them because the dual red horns look cool behind the grill, not for the sound. They look really good on a WRX/STI. They might look good on an IS if you can position them so you can see them peeking through the grill.

 

I installed them on my old is300 and hated them. X2 on wimpy

 

Hella Horns are not much louder then the stock. Watch any you tube video. I got a pair of the super tones, replaced the stock ones in my 3IS (2015 IS250). I measured the stock ones to be about 95dB. They are pretty weak when on the highway and some truck is trying to run you over. The hella supertones, I could not get to measure over 97db. They don't sound that bad, but they are not any louder, don't waste your time.