Hey there hoping someone maybe knows the answer to this odd question. Picked up my 2015 335i xdrive about a year ago. As far as I know it was bone stock when I purchased it. In stock form it felt very healthy compared to similar 335i that Ive been in. Figured it was possibly just really well maintained and/or possibly a factory freak. First mod was xhp stage 3. Feels amazing over the factory trans tune btw for anyone on he fence. Feel like that is how it should have come from the factory tbh. After some fresh preventative maintenance changed ALL fluids oil, tranny, diff, transfer case and coolant, oil filter housing gasket and belts I went full bolt on..
NGK plugsARM intercoolerARM catless downpipeARM turbo outletTurbosmart plumback diverter valveCTS intakeCTS turbo inletCTS charge pipe
After watching/reading various forums decided to rum bm3 stage 1 to get a feeler for the new mods and that tuning platform. Really opened it up from what it was but naturally wanted a little more and went stage 2 ots map next. Felt even stronger. Up top though even on stage 1 it seemed like it would pull timing pretty bad. I ran the 91octane maps since I only have 92octane here in Washington. People I've talked to said it is strange to pull timing on those ots maps as I guess they are well within safe limits? Ended up going to the dyno at 22rpd up here. Ran multiple times and confirmed I was pulling timing pretty bad up top. Dynoed 380whp and 430 tq on bm3 stage 2 and pulling bad timing. Ran new fuel and a couple tanks of gas over the next two weeks in it in case I had bad gas and we replaced the plugs just in case. Came back for custom tune a couple weeks later to see if they could clear it up as we ran out of time the first day and was hesitant on potentially bad gas. Well we must have done 25-30ish runs. after couple runs we broke 400s then 420s and finally ended on 472whp and 480 ftlbs of torque. absolutely blown away and way more than expected. very smooth up top now as well and pulls like a freight train. MY QUESTION is I'm thinking there is an upgraded turbo in this from the previous owner and perhaps they removed all their bolt ons when trading in. I didn't notice anything that stood out when installing any of the bolt ons and using an inspection mirror has proved fruitless trying to find any sort of label or anything on the turbo that would indicate an upgrade. is there ANYWAY way I could physically tell without removed parts? Hoping for some chime in as I know these numbers are well above the facctory n55 turbo and the way the power curve is matches other "pure stage 2" dyno graphs I've seen. Would love some input. If I have a sneaky turbo upgrade and not realize it that would be a wonderful present. Anybody else ever have something like this happen? Would be fun to hear stories similar.
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