Here is what the 2899205 68 manual cam sounds like:
Please note my mufflers are open, in other words, in the loud mode. I have a Dr. Gas X crossover so it tends to smooth it a bit. it is pretty crackly and snarly for a stock cam when it has no crossover. This cam picked the car up about a mile per hour so it is likely worth 7 to 10 HP up in the 5500 to 6000 rpm range. It is truly a great cam for a stock four speed car. Set your volume levels the same and you can then hear the almost 10 dBa difference between open (this one) and closed (above).