I recently put in a pioneer 4100ub head unit and my drivers door speaker is now all distorted when i crank it up, i want to get new speakers but i know it wont work with the mach amps, am i able to get new components without an amp and run it off of the HU until i can afford the rest of the system? i read 6.5 components are better than the 6x8s is this true also wats a good brand and type of speaker, i want to eventually have all new speakers and a sub

 

new speakers will work just fine off the Mach amplifiers, have replaced them many times.

6.5 comps are typically better... but there are a couple of companies that have actually built high performing 6x7 (5x7) components. Image Dynamics XS series are excellent.
All the same it will be easier to find a good set of 6.5 comps.
you best bet is to go to your local car audio specialist and listen to what he has available. do this with as many speakers as you can. you ears will tell you which you will like the best. (remember that demoing froma display on the wall will be a different sound then in car. but you will get a pretty good Idea.)