Tricky Timing Q--experts reply please

[titotonto]

I've had a timing issue with my sr20 for quite a while.

I know that factory specs require me to to set it at 15 degreeadvance. Everytime I set it there it feels like the car doesn't belong there though. As you accelerate it bogs down, the moreopen the throttle is the worse the problem becomes....the best to describe this is that it feels like the timing is way way retarded. I was explaining this to a friend and told him that at 25 degree advance the car felt so much better......he ofcourse told me that yeah if I advance the timing it would be faster, but that its not good. I already knew this, but rather that to try to explain this to him I let him drive my car. He just completed his 4th Sr20 swap and was timing it that same day, and now it turns out his car has the exact same problem as mine. To make it worse when we time the cars to 15 degrees advance, the EGT's skyrocket, when we advance it to 25 they run much smoother and about 300 degrees cooler on the EGT. Anyway, maybe someone here has some idea of how this system (ignition) truly works. As I open the throttle and with the timing light connected I notice that the ignition timing advance itself, could it be that somehow its not doing this at the correct rate????