So I built an 11.3, used a BCM standard carbine buffer kit. There was a decent amount of recoil even with a brake on the end, and everywhere I looked people were recommending the h2 buffer. So I ordered one. They also mentioned the springco enhanced spring (I don't remember the color but I think it was red).
Is it really necessary?

This is an 11.3 build that will be suppressed 99% of the time.

Parts list is simple is anyone wants to know and has any recommendations
BCM LPK
BCM carbine buffer kit
BCM h2 buffer
Aero TX m4e1 lower
SBA3 brace
Magpul k2 grip
BCM upper
BCM BCG
Ballistic Advantage 11.3 barrel
Ballistic Advantage Gas Block
BCM Carbine Gas Tube
Midwest Industries 10.5 rail
Dead air single port keyboard brake

I have built over a dozen AR's in various chamberings and barrel lengths and all run 100% and none have anything Springco

So, my answer would be NO

Thank you!

You could probably get away with an H3 in that setup.
I'd recommend the Geissele H42 spring, I love them things.

I'd also add, what is the ejection pattern?  I tuned by SBR for buffer weight by evaluating where the empty cases got ejected to.

Need?

Negative.

It just comes down to how overgassed it is.

I used to put a H2 and Blue Sprinco on just about everything, but then had a run of builds that caused problems.  I look at ejection patterns and reliability first and foremost.