I would have to say i took at least two inches out.  I almost went all the way to the body mount.  I was really dreading the job, but it actually wasnt really that hard, It took me about 6 hours start to finish.  Just make sure you check and double check that all the carpet, wires, and firewall insulation are out of the way! that stuff catches on fire really easily, not thatI know from experience or anything...