Only about 80 amps. Shouldn't be too drastic. The alternator in my Chevy Tahoe is 125 amps.
I ran a Texas Star DX 1600 v in my Chevy Tahoe with the factory alternator and it worked quite well. The new dei transistors suck compared to the old Toshiba transistors and I think they're 25 or 30% less output but they do work.