Are there other Lexus SC300s that have been converted to Supra Twin Turbo engines?

Yes.  there are scores of completed projects throughout the US.  One purchaser of this manual completed the entire conversion project with his buddy in just 30 days.  I receive emails almost weekly from other owners who are in the middle of their own project.

I'm not much of a mechanic.  Could I really accomplish this conversion on my own?

If you can read and follow instructions, and have basic mechanical aptitude, a decent tool set, and a dedicated place to work on your car, you CAN do this project.  I am a small business owner and pilot by profession, and had done little more than change the spark plugs prior to completing this installation.

How much will it cost me to make this conversion?

There are many variables to the final cost.   It is possible to find a good, low-time Supra engine with all the accessories for around $5,000.  It would then require another $1,000 - 1,500 for additional parts to complete for a stock Supra installation.  My own project got a bit out of control, as I decided to upgrade most everything, winding up with a engine that puts out a reliable 450 HP instead of the stock Supra 340 horsepower.  In the end, I had invested some $15,000 in the conversion, including complete new exhaust system and intercooler, HKS Vein Pressure Controller, radiator, larger wheels and tires, sport springs, etc.

What transmissions are acceptable?

My conversion was done on an SC300 with a stock manual 5-speed transmission.  The Supra engine mates perfectly with no modifications required.   The SC300 auto transmission will also mate to the Supra engine, however, some sources (unverified) seem to think that the auto trans may not hold up to the additional power.  The manual does NOT cover specific wiring details for the automatic transmission, but the changes would be negligible.  For the ultimate upgrade, it is also possible to adapt the stock Supra 6-speed transmission to the Lexus body.  Details are included in the manual.

What about reliability?  Am I creating a maintenance monster?

You are basically installing a Toyota engine into a like-minded Toyota-based car body.  You can expect standard Toyota reliability with the Supra engine, but with power that transforms the Lexus from an old-lady's car into a snarling, fire-breathing ultimate sports car!  By carefully following the wiring conversion charts included in the manual, EVERY system in the Lexus remains functional, exactly as stock from the driver's standpoint.

Why is the manual so expensive?  Seems like a lot to pay for one book.

It took some 12 months to complete the original conversion project.  Much of this time was devoted to countless hours of research, internet searches, and correspondence with various Supra-Lexus experts.  After completion of the project, an additional 4 months was devoted to converting all the research and experience into a format that others could use.  Obviously, there is a very small market for such information, and production of this manual has been an attempt on my part to defray some of my time and expense, while sharing my knowledge with others.   I guarantee that purchase of this manual will easily save its purchase price by avoiding wasted time, and unnecessary or incorrect equipment purchases.