in all honesty put the original exhaust back on ...get all the bits you want and the apexi fit them and drive off boost to a mapper and voila!
This is the best advice on this thread.
Buying a boost controller will actually run ok if set right, however it\'s fairly pointless on its own.
You\'ve upgraded the exhaust, which is now giving you higher boost because it has less backpressure (gases exit more easily), so the pressure difference across the turbo (hot side) is greater.
More boost = more air in the engine. To make more power, you just need to add more fuel to match the extra air, and all will be well.
However, the stock map doesn\'t have fuel settings to match this much extra air. Therefore, the fuel cut is kicking in as a safety mechanism to save your engine - because having too little fuel for your air is known as running lean, and causes deadly detonation.
Now, you could fit a boost controller to reduce the boost back down to a safe level. However, you\'ve now gone back to approximately the same (safe) boost level that you had before you changed the exhaust, so power output will also be approximately the same. Hence rather than buying another part, you could save money by just refitting the standard exhaust and achieving about the same result.
Thinking of it another way:
* The power you can make is limited by how much fuel you can inject
* The stock map only supports injecting up to a certain amount of fuel
* Therefore, to make more power you need to change the stock map with e.g. an Apexi PFC. Trying to make more power without changing the stock map will not work, but it may destroy your engine.
Technically, there are other, cheaper and less reliable ways of injecting more fuel, but you\'re really into guesswork land there, and the rotary is especially unforgiving of wrong guesses when it comes to fuelling.