kz 900 after market pipes.... improvement ?

The after market 4 into 4 pipes sound different than the OEM. (or in my memory !)
Back in my younger days, I use to remove the baffles on my triple 250 then cut in 1/2 or drill holes at the end cover on others bike.

I'm missing the original sound on my KZ900 and I would like to get  it a bit louder.  What should I do ?

The Doremi aftermarket pipes look and sound identical in my view.  But if you want a bit louder more throaty sound you might want to check out Kerker or whatever they're called nowadays.