Following up - i ended up using the 4mm x 81mm Oring on the throttle body. This did make getting the VRSF CP onto the throttle body much more difficult. One thing to note, its not necessarily just the larger Oring, but the larger Oring makes the metal lip of the charge pipe catch more as you are trying to install, so you really need to wiggle it slightly while applying a lot of force.
As for the TIC-IC and CP-IC connections, I had a much more PITA experience, and a couple of noteworthy items to mention. First, I was NOT able to get the 4mm x 59mm Oring on the TIC-IC connection to work. There was absolutely no way. I spent over an hour trying to force this on, but it was simply not going to work. I tried various other 4mm Orings I had in the 50’s mm range and none would work either. I eventually ended up putting the stock tapered Oring back into the TIC pipe. That taper does indeed go back into the TIC pipe, away from the IC, which is the logical way that makes sense for the direction you slide it on.
As for the CP-IC connection, I did end up getting the 4mm x 59mm Oring to work. And yes, it was significantly harder to install than the stock one. One interesting note here is that I removed the VRSF CP and first started testing Orings on the stock IC on the ground.
I could NOT get the VRSF CP to fit on the stock IC connection with the 4mm x 59mm Oring. Even with the IC on the ground and applying a ton of force, it simply would not go on. However, the VRSF CP DID fit on the VRSF IC with this same Oring (with some effort but not a crazy amount). This leads me to believe that the VRSF IC must be ever so slightly smaller diameter at the connection point than the stock IC, which would in turn lead to a loose/potentially leaky fit with the VRSF CP using a stock Oring. This is consistent with how easily the VRSF CP just slid onto the VRSF IC with zero effort when using stock Oring. FWIW I also tested a ton of other Orings (e.g., also 59mm but 4.5 mm and 5mm CS) and nothing bigger was going to fit on the VRSF IC-CP connection. I thought the 60mm x 4.5mm was a good contender, but it was not going to work (that 0.5mm makes a huge difference).
So to sum it up, I used the 4mm x 81mm Oring for VRSF CP-throttle body connection, the 4mm x 59mm Oring for VRSF CP to VRSF IC connection, and the stock Oring for stock TIC to VRSF IC connection. Each of those was the maximum size I could fit; trust me, I spend at least 3 hours trying different sizes, including with the components on the ground.
The most annoying part out of all of this is that my logs are no different, I am still not reaching boost targets, and I am starting to suspect stage 1 tune. I am as sure as you can be that I have no boost leaks as every connection is tight, bung plugs are Teflon taped and sealed, Orings are replaced, etc. I welcome any input on my post here:
https://f30.bimmerpost.com/forums/sh...postcount=3487
On another note, my boost leak tester failed, as I describe here:
https://f30.bimmerpost.com/forums/sh...8&postcount=14