Sounds great. I have a rear muffler delete. Starting was like mine. I figured that my alternator was weak. overhauled it myself. Now battery is charging properly and engine starts much quicker. Cool car!
Your 928's cranking over much too slow - check your battery, clean cables/connections, etc. And/or, maybe the battery just needs a proper deep charge with a smart charger - I do this with the negative cable disconnected although it's not necessary. Also, if I know I'm not going to be driving it for over a week, I'll disconnect the negative cable so the battery won't drain. Another tip is to buy a USB cell charger which plugs into the cigarette lighter and also displays volts. My 87 5-speed shows 12.0v at the dash at idle, but the USB reports 13.5v which is what my Fluke reports at the terminal in the front by the engine. Not sure why the discrepancy, maybe the dash needs to come out and connections cleaned, but I won't be doing that anytime soon. Your oil-pressure gauge is reading low, so check your oil-pressure sender connections, and if good, replace the sender. Your car sounds great - congrats and enjoy your 928! It is an excellent/fun car to drive despite not having the hp of a modern sport/GT car - don't tell anyone our secret!
Your battery opinion is right, our battery only 55Ah (smaller is lighter). Negative cable connect was untight, because unconnected in winter time. Oil pressure is ok, but gauges lives own lives. Pipe modification result: smoother sound on low rpm, sound is very raw, if rpm is higher 4000. Consumption dropped 0,3 dm3 / 100km. Power increased 20hp. X-over come from Martelius.
