Just a quick note on twin turbos...
Personally, I have NEVER installed a turbo in my life, I build N/A engines only. However, I did study turbochargers quite extensively while getting my BSME. One thing I notice a lot with individuals who have "twin" turbos on V-convigured engines (whether it be V8 or V6) is that they put one turbo on one bank and the other turbo on the other bank. This is a waste and a shame! The BEST way, (and I'm not just throwing out my opinion here, I've gone through some very extensive thermodynamic calculations on this) is to stage them! You have to feed the first turbo with every cylinder, then feed the second turbo with the outlet of the first. To get this set up perfectly, you have to know your desired operating conditions and then there is a LOT of math to be done! Also, there are some trick intercooling/aftercooling things to be done here as well.