U can go before the 12pm loh. Usually theres not much ppl during that time. And if they dont really have the full range or the particular one that u fancy, u can request them to check with cathay marina.
The ECU thing modding is really a very dark area in engine modding loh.
Thats y prices up to the seller. Its jus a re-written engine management program. Those cheaper ones are the type thats been totally rewritten. The more expensive type is the type that has been written to be integrated into the original program, by doing so its supposedly to be more difficult to be found out by the official car workshop. But then again, like i said, the integrated one will learn the driver's driving style as well since the original program is present as well. And yes, increase in hp is negligible. And yes pml warranty is up after 3 years. After that 3 years then play with the engine. Before that, jus play with handling and looks loh. Have fun