comfort and performance don't usually get along, when they do they are super expensive.

sound system and soundproofing has nothing to do with performance, but since you mentioned it I'll give you a precaution.

Make sure you find a good shop what have spare brand new panel, trim clips for replacement. A lot of shop claimed they will not break anything, in fact just simply ignore the broken plastic clips.
Don't later you isolate road noice, but get plastic rattle everywhere which is much more annoying.

Ouch it hurts!

UR market it as safety bar is misleading. Stiffer ARB = improve handling is a bold and not all accurate claims. If they happens to have the size you need, by all means. If not please don't simply install the vanilla package. That's dangerous, this is not one size fit all setup.

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My car come with 15mm rear arb. The rear is not a lively as I would like to.
There are 2 popular options 19mm and 22mm from enthusiast research and testing. 19mm will kick out the tail, but still relatively neutral. 22mm you can basically do lift-off oversteer at will, it is the go to choice for auto crossing goers. There are also 22mm with double link mounts, the further mount would make it behave like 19mm for safer street use.

I didn't change in the end, knowing probably dangerous when my family members drive the car.

You see those are properly calculated stiffness, where buyer are informed what to expect after the change. Not a vanilla solution.

Although the rear is not as lively as I wish, but the arb chosen is balance for street use. Upgrade the rear make it more fun to drive, but one simply put a front tower bar without upgrade the rear first, that would upset the balance. The front already have 24mm arb stock, want to touch the front must upgrade the rear first for that particular car. The key is balance, know what is your use and what stiffness you looking for.

Mazda tends to have more fun setting, remember seeing 22mm front arb + 18mm rear arb stock.