My car (mods in sig) is about to hit 120K. So far it has run perfect with no problems except an opti and waterpump replacement which is pretty standard. Oil Pressure is fine, with absolutley NO leaks, new O2's, plugs, wires. But, fo some reason, my car just feels sluggish all the time. I am about to get new gears which i hope will change the way it feels, but im wonders if there is anything i can do to make the car feel new again? Will changing the valves, RR, valve springs, etc. on the top end give me a better feeling engine? I also have a slight exaust leak from installing headers....how much could this effect the way it performs?

 

Exhaust leaks in the headers before the O2 sensors can play havoc with the O2 sensors, causing a "false lean" condition that causes the PCM to load it up with fuel it doesn't need. That will definitely cause a "sluggish" feel.

Might be a good idea to have a scan done to generate a log of the critical sensors over a wide range of operating conditions. That might point you to the cause of the slugishness..... running too rich, knock retard, etc.