What could detonation be coming from? Cause whatever it was, it scared me cause I thought something was gonna break.

 

Detonation can be caused by carbon build-up inside the combustion chamber, which effectively raises your compression ratio, which can cause detonation. GS-R engines have a knock sensor to retard timing to help prevent that from happening (which is what it does if you use less than 91 octane fuel), but it may be too much for the sensor. I'm not real familar with how the system works, though, so I can't be sure. You might try some fuel system cleaner to help get rid of any of that stuff. I use Valvoline's SynPower fuel injector cleaner every 3K miles (every oil change), and every 12K miles I substitute that for their fuel system cleaner. After using it for awhile on my old car, it allowed me to return to a lower octane fuel without any knocking or pinging problems. I use it regularly on my GS-R as preventative maintenance.

 

I'm a bit low on cash right now...so what happens if my valves need adjustment, but I don't do it...?

 

your car runs at less than its potential. Thats about it. Might get worse gas mileage too

 

I think I am starting to notice that. I'm almost at 70k miles and haven't re-adjusted the valves for the 60k tune-up. And I can only get abou 250 miles out of a tank of gas at the max.

 

well the first time i adjusted the valves it was a noticeable increase in kick...esp on the freeway in 5th.

Unfortunately I;m at 102k now and getting 250 miles to the tank yet my valves and everything else is good...no idea where my mileage went =(