Bolt-ons are great. I'm sure a down pipe, FMIC upgrade, cold air kit and a tune will make a good improvement but some people will want more. This thread is about the limitations of the stock 1.6 Ecoboost and how they can be addressed. Its speculation because no one has been pushing the limits and talking about it yet. #1, no tuning software. We can't tell what is going on with the ECU maps so we can't see where Ford tuned around the hardware. COBB has the Accessport and soon will have Accesstune Race which should solve the tuning issue. #2, a really small turbo. Looking at dyno curves and the description of the COBB 93 octane tune (20.5 psi boost at torque peak tapering off to 13.5 psi at red line), it looks like the compressor is too small to push a lot of boost at high rpm. A bigger turbo seems to be the answer but going too big will mean sacrificing that almost off idle surge of torque. A first place to look is the Borg Warner K03 that is used in the Focus ST and capable of 300 HP. Looking beyond that, Borg Warner's EFR series has a really impressive set of features like a low inertia Titanium Aluminide impeller, dual row ceramic ball bearings, a good integrated waste gate and very nice thin wall stainless turbine housing. The EFR 6258 is the smallest one available but good for 350+ whp on a Miata 1.8 with full boost achieved around 3,000 rpm. If we can find a turbo that can maintain the 20.5 psi boost and 220 ft-lbs of torque until 6,500+ rpm, 270 whp is possible which is a reasonable goal for the engine I think. #3, the high pressure fuel pump. With a tiny turbo I don't think anyone is going to find the limit but looking at the Bosch web site, it seems like they only make one basic pump and the volume supported is determined by the fuel pump lobe on the cam. The Ford Focus ST seemingly has the same pump and can support about 300 whp so if the Fiesta runs out of fuel, the fix might be as simple as a custom cam with an exact copy of the Focus ST fuel pump lobe. #4, fuel injectors. Hopefully these do not limit anything because they are application specific. #5, traditional turbo plumbing issues. Exhaust restrictions, cold side plumbing, etc. If you are going for a turbo upgrade, making nice plumbing seems like a no-brainer. Increasing the size of the throttle body and porting the intake manifold might be places to find power. Porting the cylinder head might be worthwhile too. It seems like there are going to be several FMICs to compare, hopefully one will be appropriate at the 300 whp level. My guess is that the next level in performance is a custom exhaust manifold, EFR 6258 turbo, high flow down pipe, high flow exhaust, FMIC upgrade, good plumbing, possibly a custom cam and a tune. The manifold, downpipe, and plumbing need custom fabrication and finding a custom cam might be hard but nothing is really out of reach. Since I can do a lot of the custom fabrication it seems like only a question of time and money ($1,450 turbo, probably $1,500 for stainless and intercooler, $625 for tuner, maybe 50 hours of fab). If there are any additional issues to address, known good parts sources or other ideas, this is the thread for it.