Oh for sure I don't know when I'll personally have the "need" for 600 HP I was just talking hypothetically as to what scenario a modern engine swap becomes "practical". I've been having tons of fun with "only" 300whp (uncorrected at 5000' elevation) in my Duster and it's been reliable as a hammer for almost 5 years and 12k+ miles. Hence why I have no rush to swap my 5.7 Hemi or add a Procharger. Although one big upgrade I will definitely be doing once funds allow is a 5- or 6-speed manual with overdrive. I built/am building my Duster for auto-x, track day type stuff and would also like to try out 1/2-mile drags at some point and the 904 with cheapo loose 2600-stall converter it currently has sucks for those applications.
Although once I move to Texas where 600+ HP street cars are the norm I may feel more compelled to up the ante lol. I can have plenty of fun driving up in the mountains in CO by myself or ripping around a tiny road course at PPIR but Texas is a different world in comparison. I've never been one to feel the need to compete with other cars all that much and just enjoy what I have but I'm only 31 and I'd like to at least try my hand at having something fast enough to compete with modern fast cars. Maybe it won't be satisfying and I'll just go back to playing with my stuff by myself lol who knows but I want to give it a shot eventually.
