Before it was cleaned with autosol it looked "normal". Thats looking from the angle the photo was taken.

If you are running 15/16" wheels the 3.5" will be fine, if you are running 17/18" wheels, the 4" will look better.

Yes i know it sounds daft. But when there is a 3/4" shot of my car, the exhaust looks horrendously massive. But its mainly as the 15" sharkteeth are throwing off the whole look. Seeing my mates car with a 4" and on 18" wheels, its proportionally better looking. The same way if you ran big wheels and had a 3.5" tailpipe, it would look "too small"

All in my opinion of course.