Not trying to be a dick, but you sound young and immature. We were ALL THERE at one point, and now try to guide impressionable young minds like yours.
If these cars are not cop magnets enough as it is, you want to go and announce it to the whole town, then not be able to run away fast enough. Dont poke the bear unless you can get away. Its way more fun to have a fast car that nobody suspects, than a slow car that attracts attention.
As far as the rest of your system, you sound like you have a completely stock LT1. a 3" single will support something like 370 hp with zero loss, assuming you have a good flowing straight through muffler, which you dont. You have a muffler that actually flows LESS than stock. A single cutout in the I pipe below the passenger rear seat will be perfect for your setup. You will have enough pipe behind the O2s for the computer to take an accurate reading. You dont need dual 3" cutouts until you have something like 600 hp. I ran that setup for years, and would uncork my exhaust when I got to the track, or was just lining up for a race, then cork it back up as I drove home unsuspected.
Or you could just be a ****ing ricer and annoy the shit out of everyone and anyone you encounter and let everyone know you ARE a giant bag of doosh, like all the corollas you see now with the tow hook on the back.