Neil,
Good points and well argued [
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Different views are what makes the on line posting community such fun
I am a bit of a cynic too - very mistrusting of tuners claims until I see the evidence.
One definitely needs to research the car and its potential first and then look carefully at the supposed beneficial tweaks
I wasn't convinced so the first time I dyno'd the car I got figures with the remap settings on standard and optimized for the Porsche. The difference 22bhp. I have the graph. Conversely the exhaust change to Milltek was estimated to about 8bhp gain on its own, no where near some of the claims I have sen for that product (as you rightly say its the combination of changes that gets the bigger gains).
The is a second side to my cynicism - the manufacturer. If Porsche made the best performing car it terms of BHP and track times it could for the price point of each car at the expense of all other considerations. I'd agree with you that little gains could be found by tuners.
However these cars are made to a budget and most (bar the GT2/3) are a compromise between practicality, comfort, safety and performance - take for example the standard set up of the cooking C2/4/S is tuned for under steer so if a granny drives it down to the shops she won't kill herself and no one gets sued. The famous RMS issue, which can be cured by changing the 50 pence standard unit for one costing approx £12, funnily enough Porsche did not fit this to their cars from new. The air intake/induction boxes on most cooking models strangle the engine and reduce the cars performance. However they are reliable, protect the engine, fairly robust in a wide variety of climates and conditions and above all very cheap to make. You can buy much more efficient induction systems but have to choose between certain compromises and they cost a lot more.
The same is true with the software and software tweaks. A manufacturer has all sorts of regulations it has to comply with and aims for one superset of code for all markets. To protect themselves legally they will apply standards above those of the worst restrictions from certain countries - The after market tuner is not so heavily regulated and is allowed much more freedom in setting the parameters they'd like to use. So you'd argue these would be the settings Porsche would use as a default, if they were allowed to but they aren't.
In reality its the torque gains and the revs the gains happen at that make the biggest difference to how the car feels on the road. Your example of the M3 vs CSL, the guys might well have been getting the same hp but at the cost of less torque lower down the rev range, making the car slower on the road not faster.....So on a Millbrook Mile they might get good 0 -100 times but might still get mugged by a well driven 330i on the road....[8D]
So long and short of it - you pays your money and takes your chock ice - remaps work for some people and not for others. You may get gains from them but for an N/A car its of the order of 5% power hike, give or take. But mainly it improves throttle response, drive ability and feels quicker. So depending how you like your car to drive, its worth the money or it isn't. And be wary of really high power figure claims, its normally wishful thinking or at the expense of other important factors.
