Don't know of any currently made like this, but during the '60s most
Honda twins (all 4 strokes) were 180 degree layout.
e.g. CB72/77, CB175, CB250/350, CB450.
The exhaust sound was the norm - V twins were the rarity then.

Jordan

Mike wrote:
What well known parallel 4-stroke
engine type use the opposite, one up and one down? Sound must be quite
distinct.

O=={o] Hot Rod