My Camaro is lowered 3/4 of an inch, and my Formula is lowered about 1 inch. Lowering makes the most difference while taking high speed corners (on top of making the car look wicked). But, it usually kills your traction especially on launches. If you have a spring compressor, you can swap a set of springs out in a garage or probably even a driveway. I did my Formula in a garage about a month or so ago. It's a pain to do, but its better than forking out how much shops will charge you these days.
I don't have any new pics of my Formula since I lowered it an inch a month or so ago, but here's some pics of my Z that is lowered 3/4 of an inch.
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95 Z28 M6, 383, D1SC, FMIC, ect., ect., 614 RWHP with the stock PCM and pump gas!
98 Formula WS6 M6