[JFP in PA]

Originally Posted by Mike101

Last year I set out to tune my Boxster and here's how?

I run a 2002 boxster S which makes 306 bhp.
I run an Evolution air intake, Fabspeed 986 cats pipes and mufflers. And ecu remap.
20 bhp from ecu alone. Massive power increase at 3000 rpm +100 bhp to 250bhp at these revs.
At 5000 rpm car makes 300 bhp.
You have big improvement in mid range power. Absolutely fantastic on road.
Evolution air intake makes about 8 bhp on stock
The biggest boost is using good quality big diameter hsl 200 cel cats, probably plus 20 bhp.
Muuffler plus 8 bhp.
The problems you have though
Are deafning noise levels from cold air intake at over 5000rpm
Below 3000 rpm you get resonance, very boomy, from exhaust.
The oiled air filter can cause maf problems, if oil gets on maf and (loss of power)
Changing over old headers is tricky as steel bolts tend to corrode in aluminium engine.
The last down side is cost if you by cheap parts you get nowhere.
Check out fabspeed you tube video of 986 tuning.

The gains are made on the exhaust side of system, especially cats.
For intake side you could get some gains by simply installing bmc air filter into existing air box
I see people buy larger throttle bodies and plenhiems. But the standard arn't restrictive.

My choice is good ecu remap, and replace both lots of cats with single pair of top quality 200 cel units.
Going down fabspeed route will work but will cost. But you are guaranteed plus 20% power

I will try to post dyno power curves. You will see power up from 150 bhp at 3000 rpm up to 250 bhp after the mods. Simply staggering for simple bolt on mods.
You will find a lot of sites making claims of this and that.
But most of their cheap parts are not worth a dime.
For example beware cheap undesize cats smaller than the originals, not much gas flow i guess
Also beware cold air intakes made of aluminium, aluminium absorbs heat from engine, so how are these cold air intakes, etc etc. Or course some of these cheap parts arn't that cheap either.
So the answer to your question is.The missing 50 bhp is found largely on the exhaust side side of system and by re-mapping.
And yes the car was de-tuned by Porsche so as not to compete with 996, which at time cost twice as much.
How Porsche can make such a great car and cut nuts off it, you can only wonder.

Good luck with that....................