Probably your best bang for you buck.
But I'd mess with you head unit first and check your hpf set points. It should be around 80hz to keep bass out of the midsaybe higher if they still sound muddy.
I'd also lower to gain for the rear speakers so the fronts sound louder. The rears are probably very bright and over power the fronts.
And jbl are known to have quite a bright high end frequency response so you may need to eq the top end down to keep it from piercing your ears