What I was going to say, is already up there.
You have not done any mistake by purchasing MS-8.
My car is without MS-8 and I have listened music in a car with MS-8 and certainly SQ is far better in that car.
If you bought it, go for it.
And as Kaigoss said, go for Focals, and you can turn the treble down if you wish to do so.
Rest up to you S1. If at any stage, you plan to dispense MS-8, give me a shout and I will check my finance situation and may take it from you.
There you go, you have a cusomer + some good advice from kaigoss.