[E93_M_Sport]

I need the input of those how likely know better then me. I live at 4500ft above sea level and I am looking for recommendations on turbos. The car is FBO with inlets and outlets running on octane booster and MHD 2+. I do not have access to E85 (trust me I wish I did) so I bump the terrible 91 octane up with a validated octane booster. The factory turbos are just out of steam at 19 psi at 4500 feet up. I know that it is like spinning them to 21 psi at sea level. I am looking to upgrade the turbos, yes staying twins, to something that is reasonably responsive down low and pulls to redline. I would like to go to the upper limit of what the factory fuel system can handle possible 500 whp. What should I be looking for in turbos. Also will I need to have a second tube for when I drop altitude? I appreciate all the help I have read through all the posts but my situation is unique due to my altitude and my lack of E85 or even 93 octane.

[iqraceworks]

A set of RB Two turbos will get you close to 500hp on pump gas, maybe step up to RB Two Plus turbos if you want a little more power. They are some of the best twins for the N54 platform. Machined, assembled, and balanced here in the USA. They respond as fast as stock turbos, and pull like a train all the way up to 7K rpm. My car ran 10's at the track with nothing but standard bolt-ons and RB TWO turbos with a good E40 tune at 25psi. That was at 1000ft elevation.

No, you will not need a separate tune if you change altitude.....the DME will adjust things.

The fuel system isn't what's going to hold you back, it's the 91 octane fuel that's going to be the limiting factor. These motors love octane. You are probably going to be limited to 475-ish HP if all you have is 91, especially at high altitude.

Spend some time researching custom tuners....a good custom tune makes all the different in the world.

[E93_M_Sport]

That is great information. I have been looking at the RB 2+ turbos they look well built and considering I just did VRSF 1.75 inlets they appear to work with the high flow 1.75 so I won’t have to swap them for 2.0.