You may not feel each piece individually, but together it all adds up.
If you drive a stock 86 at 2750 lbs, then immediately drive one at 2500 lbs, you will notice the difference. Particularly in any kind of maneuver that involves weight transfer (think S turns or slalom).
Now ponder this. 130 lbs off 2750 doesn't sound like a lot. But that's almost 5%. Look at it this way:
170whp at 2750 lbs is roughly 16.17 lbs per hp.
170whp at 2620 lbs is roughly 15.4 lbs per hp.
170whp at 2550 lbs is 15 lbs per hp.
And this doesn't take into account the inertia advantages for breaking and cornering.
Looking at what @
Anthony did, taking 150 lbs or so off the car while maintaining comfortable daily driveability shouldn't be all that hard. Might cost a few dollars, but a lot of this stuff the people on this forum were going to replace anyways (ie, wheels, tires, suspension, exhaust).