The HD428 isn't a bassy can. The HD418 and the HD438 are the bassier cans in the line.
I'm not sure what you mean by the tape mod.. but if you did remove the tape that covers all the
three holes, it will give the bass a fuller sound. Some call this bloated and muddy, some like the
"bloated and muddy" bass sound, lol.
What I do is tape the hole towards the front of my HD438 and leave the back two open.
I get more bass without making the sound too muddy.
You won't get better extension by doing the mod, you'll get a louder or fuller bass sound. In other words,
if your cans aren't that bassy (428/448), the mod will give you more bass, but it won't give you deeper bass.
The dime mod won't make a big difference in the sound, since the gauze that covers the drivers are rather
thin.
Anyways, don't let others put you down. Some people don't like the HD4*8 cans because they've tried various
other headphones, some exceeding 300-400 bucks but I like my HD438s. Comfortable, not clampy and imo,
very good sound for the songs I listen to.
What I would do is bring your friends over to your house and let them listen to the HD428 and the Beats in a
dead silent environment. If they're total bassheads, they'd probably still prefer the Beats but if they appreciate
detail, I'm sure they'll find that the HD428s a good pair of cans, for a lot less.