I'm currently a senior in High School and have been playing trumpet for almost eight years, and am currently the lead in our concert band. For my first Few years of playing I used the traditional Bach 7C. I then moved into a 3C as most players do, and eventually into a 3D. I then went on to use a 5A4 from Yamaha Japan. The cup was extremely shallow and made playing in the higher register much much easier. However, my playing in the lower register suffered greatly, as did my tone quality. I sometimes compensated by showing off and playing things an octave higher. However, my band instructor told me to go back to the 3D last year. And I did. My tone quality got much much better, although my range suffered. Having played the mellophone for our school's marching band for this first quarter of the semester, and shirking my trumpet duties as such, I find difficulty in playing in the higher register. Although I realized today, every time I go up, I always press the mouthpiece to my lips. So much so it hurts. I do this because the cup is too deep, and I don't feel I'm filling it quite like I should, and especially not when my lips are so tight as to hit the C and up. However, the diameter of the mouthpiece is wonderful.

So basically I'm looking for a mouthpiece similar to a Bach 3D, but slightly shallower, maybe wider in diameter too... get more tone quality out of it... and maybe with a better backbore. Not really sure what a backbore is but I would obviously need a good one...

Anyone have any ideas or suggestions?

Talk to your director about a backbore.
Also, try mouthpiece comparison charts, or get the specs from the Bach wbesite, and compare it with specs from companies like Shilke and Yamaha, who are known for quality mouthpieces at a rather cheap price.
Is this for legit stuff or marching?

I was reading about an Assemetric Mouthpiece, it supports the lower lip putting less strain on the upper, giving you a bettter sound, range and endurance.

I want to try it out, I told my band director about it, and he said he'll look at it.

Here's a link: http://www.wwbw.com/Asymmetric-The-New-Trumpet-Mouthpiece-i74983.music

and really, if you cant hit whatever you need to hit on a 3C, you need mroe practice.
try the LM-77, its a 3C designed for marching. don't get any of the others.
http://loudmouthpieces.com/trumpet.php
its rather expensive, but the memphos sound drum and bugle corps uses and loves it.
if you want a mouthpiece for marching, its the way to go.
seriously, don't use cheater mouthpieces.

Well I don't march (we don't have a marching band sadly =( ) But I do want to march when I get into college... If that's even possible...

At any rate, those Asymmetric mouthpieces look pretty sweet... The lead 342 says it has a medium cup depth, great for any situation, a wide opening, and a dual modified straight backbore for a good low register. I need all of that! And it says it helps greatly with the upper register as well as having a big bright sound... exactly what I need as a lead player!

I'm going to do what you guys said, to compare these specs too the Bach 3D... hopefully it'll be just what I'm looking for =)

And those LOUD mouthpieces look amazing but I'm not a marcher and I'm also not wealthy enough to drop a buck 50 on a mouthpiece ... Although my parents might... STILL, not a marcher, sadly...