[panameras]

Nick is spot on. First graph is showing figures in KW, all 4 runs were performed within minutes of each other, no variables been changed and 167kw was the best of them.

Second graph is showing in Horse Power. 224hp(167kw) vs 231hp. Only modification been a set of aftermarket headers.

Other than different room temperature and humidity, I tried my best to keep everything else constant. same type of fuel (BP Ultimate 98RON). same set of tyres with the same tyre pressure. I don't drive the car much so there were minimal tyre wear (about 2000kms of 80% highway driving).

Therefore there were indeed variables in test conditions, However the most important finding is what PAT mentioned "There's a difference of 25+ hp at 103 mph in the measured gear! Not to mention all the area under the curve throughout most of the range tested."

Now for the non believers, yes it is possible to get a few horse power gains here and there due to a cooler room temperature but looking at the graph how do you explain major gains of up to 25hp across the entire rev range. If you still think it was due to margins of error, well, you obviously know better than me and I have no reason to prove to you any further.

Im not going into too much details of the brand of headers I used as Im not promoting anyones business. What I can say is they are 4 into 1 design headers that you can buy off ebay for around $500US (I believe there are at least 3 different vendors that are selling them under their own brand names but are sourced from a same manufactorer) Again Im not associated with any of them, just trying share my findings with fellow boxster owners of a worthwhile performance "enhancement" that I would recommend.