According to the Internet, the part number for our turbos is: A1770900080

This is a BorgWarner part (their part number for it is 18509880005)

I see the part listed here; https://www.turbomarkt.de/Turbolader...der-476-560-PS

I was wondering if anybody knew the size of the turbos (the housing, the impellers, blah blah blah) and how much boost the stock map runs.

I contacted Borgwarner and they wrote me back after a few days:

Compressor Wheel: 56mm OD / 41.7mm inducer
Turbine Wheel: 50mm OD / 44.5mm exducer
Turbine housing A/R: .57

S models run 21.8psi
Non-S runs 18.9psi

Nice! Thank you! What do a typical stage 1 / stage 2 usually run? How many pounds extra over stock?

What are your thoughts on throwing something like this on our cars: https://www.precisionturbo.net/Stree...PT5862-CEA/634 ?

I just need to figure out how to get compatible M177 brackets/housing, yeah?

You know that boost number isn't indicative of total flow though right? I A larger turbo can run at the same boost level and have much more flow = power.

I did not know this but it makes sense.

So you are saying you can upgrade your turbos but not re-tune your car (aka ECU requests same amount of boost) and make more power over stock? or does ECU calculate flow and pull back the amount of boost requested?

My familiarity with ECU configurations stopped about 10 years ago ha, these modern ECUs are incredibly complicated. The short answer is no, you shouldn't upgrade your turbos without a retune, because the car will not know what to do with the extra volume created. For example a friend of mine upgraded his turbos on his 17 C63s, and made the same whp as stock...then after tuning made 150whp more. You can run small turbos at 30psi but they won't be able to keep up with necessary flow volume. Larger turbos at 20psi will make more power than small turbos at 30psi.