People routinely get around 100hp from EA81s with a cam change in atmo form. Turbo engines, done properly, gain hp not directly proportional to MAP as boost overcomes the pumping losses on the intake stroke as well. I've seen a nearly a doubling of hp at only about .6 Bar of boost on several engines I've built. The long block weight of of an EA81 is around 140 lbs., the EJ22/EJ25 SOHC 188lbs. The figures on my website assumed a heavier and more expensive PSRU like the M300 which is not needed at these hp levels. The SPG gearboxes are about 25-30 pounds lighter than the M300. With attention to detail, both of these conversions would weigh well under 300 pounds which is the target FF weight. 91%? not sure where you get that figure from? Check your math. 165 X .82= 135hp which is more than 120. Even at 5000 rpm, we'd be over 120hp. Also, the latest atmo EJ25s put out 175hp so theoretically 143hp at power peak rpm at 5500 feet. Also account for reduced exhaust back pressure with altitude which adds a couple percent more hp. As a reference, the component weight of my engine, gearbox, turbo, intercooler, oil cooler, rad etc. including starter and alternator is around 324 lbs. I have some rather heavy turbo brackets and a steel intake manifold. The EA81 with SPG gearbox is around 80 pounds lighter and would also require lighter coolers, smaller turbo etc. because of the much lower hp.