FINANCIAL ANALYSIS If the turbo removal and other modifications do result in a HP change from 435 to to 350 natural, 350/435 is about 80% which means fuel economy should improve about 20%...maybe alittle more if you can run at a lower RPM.... Let's assume the modification (done professionally) costs $1,500/engine or $3,000 total for two. ( I have no idea what it costs, don't use this number.) Let's say you estimate using 2,500 gallons annually at $1.50 without the conversion. A 20% savings would be 2500 x 1.50 x .2 or $750 savings annually....it would take 3,000/750 or about 4 years to recoup your costs of conversion.... ....plus you won't have any turbo repairs....and maybe you can sell them (two per engine l) on e-bay!!! The intercoolers alone (also two per engine) list for $1,000 each (actual figure, from five years ago).... Cheers, Rob Brueckner 1972 Hatteras Yachtfish Rob hit this nail right on the head. Unfortunately I haven't heard back from the guy that did this so the total cost is up in the air. Anybody out there know what it would cost to do a COMPLETE downconvert of a 435 to 350? This seems to become a financial analysis. But as fuel costs continue to rise it makes more sense. Thanks Ed