I have to say I love the carrera GT V10, its my favourite sounding engine.
YouTube - White Gemballa Mirage GT
Before looking at a GT40 I also considered an Ultima with a V10. I wanted to fit a BMW M6 engine and but after speaking to a guy at a company called Auto Bionics was put off due to the complexity of fitting such as modern engine with all the electronics.
Auto Bionics are doing a cracking job getting their V10 in the Ultima though, can't wait to see the finished car.
..:: Project ABV10 - PART6::..