An adjustable fp regualtor is a good thing to have if you have a scan tool and experience tuning the car. For newbies it should be set at a FP that your chip or chip burner recommends and then NOT TOUCHED.
Playing with the fuel pressure can reduce knock, but that is a side effect and not the real reason Fuel pressure should be changed. Fuel pressure should be raised or lowered to ensure the right amount of fuel is being delivered and not drown the engine in fuel so it doesn't knock...but I digress.
The proper response to knock is lower the boost or add octane. remember that, there will be a quiz later.
No, flowmasters shouldn't be your first choice. A 2.5" dual outlet cat back with straight thru performance mufflers like ultraflows or maxflows will provide more HP than a Flowmaster system. You want to reduce backpressure after the turbo as much as possible. Flowmasters are designed to make backpressure.
Here is some help with
abbreviations
The best resource for reeading up on any tech questions you may have is in the tech section of
GNTType.org Use the pull down menus for specific tech areas like electrical, engine and performance recipes. Lots of great info there.
Pops are never good, but it could just be an intercooler hose "popping". TTA89 blew one off one night and he thought he broke his transmission. I even think he got a tow.... If the hoses are still black with orange inside, they probably need replacing.
Bottom line is, don't spend any money on "bolt-ons" and gimic parts until you know the car is in perfect working order. Then set a realistic goal and buy the parts to achieve that goal. Good luck, it is a lot of fun!