Right now I am running a alpine amp 50x4 watts
4 Polk db571 s
Question is looking for a little more sound.
Would I be better off bridging the amp for 150x2 to the front speakers
And running rear off head unit?
Leaving it the same and Installling better speakers or larger amp to run all four speakers?

Or save up for sub an amp?

 

Get a sub

 

I may in the future but was more wondering if bridging the amp would be worth the effort or will it sound bad

 

You can try it different ways till it sounds best to you. Those speakers dont need or handle 150 true watts. Which alpine amp, what head unit?

 

Kenwood ddx512 head the alpine is Mrpf300

 

Now that I look at the ratings looks like that amp is just about max for those speakers maybe I will look into a sub amp package.

Question that amp has pre outs for a sub amp so I can just run rcas from the alpine to another amp to power the subs correct

 

You can use the pre outs to run signal to the sub amp, but the sub amp will need separate power and ground connections. Your ddx512 should also have a sub output if you want to use it.