Bruce,
You can order the chip at TurboTweak.com. The order form will ask you specific questions about your car to ensure that it is right for you. Even if your car is completely stock, TT chips are known to improve idle and overall performance. The stock chip from 1987 has ignition timing that is too aggressive for todays blend of gasoline, and most stock-chip GNs will get detonation/knock even with 93 octane, because the timing in the chip is too aggressive. The TT chip will address this issue.
It's nice that your friend made those chips for you, but I can't say whether or not I'd use them. You know the guy, I don't. If he really knows what he's doing, then maybe they'd work. But TurboTweak chips have a very good reputation in this community.
If you aren't worried about passing emissions with your car, I'd go with a test pipe over a high-flow cat. Not sure where you heard that the test pipe will sound "annoying", yes it will be a little louder but the mufflers will still provide a decent exhaust tone.
Your wastegate controls your maximum boost. Installing a chip programmed for higher boost won't make you "overboost", the wastegate is still going to open at its normal setting. If the chip alone could increase your boost level, then nobody would need to run the adjustable wastegate.
If you're concerned about "blowing it up", make sure you install a high-performance fuel pump with upgraded wiring harness, adjustable fuel pressure regulator, and get a ScanMaster to monitor your engine data.