Michelin SS fan here. We have the same rims. Car handles much better with 275/35R19 up front. The 295's on the 10 inch rim feel unstable. Michelin lists it as ok but the set up does not feel right. They make 305 for the rear. Rain or dry they handle great.
I have had Corsa extremes for several years. My personal experience when you drive normally they sound good and are not loud. When I stomp on it to WOT @ 7,800 RPM they scream. No drone. If you are looking for something a little less aggressive Corsa sports aren't as radical. Go online and...
My Corsa Extreme cat backs pop and crackle anytime I want them to. Put it in Sport mode or use the paddle shifters.A hard downshift is glorious. Also Lund Tuned.
"he left the mufflers a bit sideways, thought it was strange" - This is what we call a clue. If something appears out of place always investigate. This rule has saved my ass several times. Glad you are ok.
To give you an rough idea My 15 GT premium automatic ran a 118.2 @12.00. I weigh roughly 225#. I'm running a Lund Flex Tune, GT350 CAI with LU47 injectors. With the upgrades I needed MT drag radials to catch traction. Not sure what the DA was. With the A10 you should be in that neighborhood.
Zero attitude issues dealing with Lund. Other than them forgetting to turn on my O2 sensors and getting the Louisiana Inspection fail sticker of shame all has been good. I emailed them and requested the O2 sensors be turned on. They sent it back and I passed.