Originally Posted by Drawn05
Please explain why you think this?
because if you don't upgrade all of your parts they act as bottlenecks.
They can tune the engine all they want but there is a point of diminishing return. At that point you are just increasing the chance of ruining the engine for no reason.
The N52 isn't really tunable, especially since the engine is part magnesium that makes it lighter, but can handle less power load as well.
But you are right that the tunes are somewhat conservative, but I think the majority want this as most of the cars are daily drivers. So, you probably could ask for something more "aggressive" but there isn't really a point unless you have full upgraded parts to complement.
Now, if you really want to upgrade the engine itself, then it would require lots of $$, such as for bigger injectors or something.
Another thing to note is the transmission. I believe the 130i uses a better transmission then the 125i and 128i and additionally different gear ratios.
I think 275 HP is probably the normal limit. Intake, DISA, full exhaust, and a good tune. After that, you are talking about serious $$ which at that point I would just get a 135i or something :P
Intake ~250, DISA ~400 i believe, Exhaust ~1000, tune ~800.
Thats a lot of money for only ~50 hp gain