I put the factory diameter round speakers but from Infinity in my fronts. Even though they lack the range, their overall fit & finish, and sound quality is nice. Can't complain. They were loads better than my old kenwoods which literally rotted away, sitting in a cool garage for 3 years. Brand new speakers, rotted in 3 years. Wow.
To mount my Infinity speakers, which were too tall for the factory space (they ALL are. DO NOT believe the websites that tell you "these fit in your car" because they DO NOT.) I had to mount some U nuts on the speaker mounting flanges, get some small but thick rubber o rings as dampers, and mount the speaker with the mounting flanges underneath the dash, not on top like the factory, utilzing the o rings for not only the proper depth locators, but to insulate the speaker from the mounting surface. It was a moderate pain, but not as bad as I thought. I actually think wiping all the fingerprints from the glass in that hard to reach area was harder than mounting the speakers.