every engine is designed to have as much useable power and torque across the entire rev range as possible, but it is always a compromise to get the best balance between the 2. the twinspark is meant to have the best of both worlds thanks to the variable valve timing.
imo the head and map are both biased towards high rpm power rather than low rpm torque. you get the tell tale surge at roughly 3500rpm.
increasing power at the expense of torque will worsen the surge effect and will also make it occur at a higher rpm. if you are thrashing your car in a straight line then you'll never be at lower rpm so it doesnt really matter, but if you want a driveable car that still pulls low down then this is an issue. what you aim for depends on what you want.
Thank you for taking the time to explain, its certainly enlightened me.
So thats why my 2.0 TS seems to go abit barmy at 3500rpm then? the difference is very noticeable as soon as you hit and pass that target rev range, and seems to increase and get more aggressive the higher the engine revs.
Also, where would cams figure in this? I was considering some headwork and cam replacements next year. Would i benefit from this or in this case would i be best keeping things as they are? I love how the cars engine behaves now. I want to make the power more pronounced, but keep the delivery the way it is... Just have more of it.
Personally i like the way it behaves. It gives me a sense of fuel economy lower down, so if i want to just potter about it still goes well. But when i open it up fully the noise, and the extra kick around 3500rpm onwards makes me smile everytime!
So bearing in mind i want to keep it this way, is there any suggestion on your opinions as to filter replacement? I'm not interested in additional noise as a priority. I just want something that suits the engine well, something it benefits from.
Would i be best sticking to a aftermarket replacement filter, or would a CDA really be the way forward?