Update and edited my last post.
I had the first and only DHM EFR and now wish I had kept it as the tune could of been far better, according to VDyno it made 320 WHP on 91 at 4700 ft which is damn good but it spooled late and hard making it tough to drive in some situations. The new owner used a better tuner and fixed the bottom end a great deal, still some lag but far better and smoother so more controllable when it did kick in.
Knowing what I now know I wish I had stuck to my original plan and built my own manifold for the EFR as it would of been equal length within mm's and a twin scroll like the last manifold I spent 50 hours on. The EFR can work perfectly well with its built in WG and Bypass valve so it would of been relatively easy.
I am going back to dept free so I can stay and enjoy being retired more and having one vehicle that I love but just to small when we have two 100lb dogs, go over the snowy mountains in the winter, I just need something different so the car is going back up for sale soon, $50k, at least 1,000 hours but likely many more invested, 15k miles on it now, going to lose my arse on it but I need something else and where I live you can hardly have fun without being seen by an LEO or reported and they are starting to know the car.
IF I was in the right place and time in life to keep it the GTX2860R Gen 2 would already be on it but I can make that happen for the lucky one that wants a very developed car for CHEAP!
OK, back on topic, C39 for lower cost and damn good power band, GTX2860R Gen 2 for those wanting more top end and good response, possibly custom EFR to save some weight, cooling less of a burden, right setup would be killer but might be a bit over the top in cost in the end.