About 10-15% in the middle to upper revs with the right exhaust. JUST enough to keep from driving around in 4th gear all the time.(mine does exactly 65 at full throttle in 5th on a 2-3% grade)
- When you install a tach because you need it. This goes with the getting on a freeway comment above.
Mine, btw, is perfectly safe to merge or get on a freeway though I do have to not be afraid to rev it upwards of 4500rpm at times. Those miserably short onramps on the Pasadena Freeway(110) come to mind.
Not kidding. Everyone rolls through this at 5-10mph.
the 110 is always a pleasure to drive when you're heading home from a Dodger game.. lol