This!
While not elegant nor sexy, performance is basic physics. You have done all the hard work, now do the dirty stuff. When that's done, rebuild the engine with as much displacement and rpm capability as you can afford and call it good. Horsepower=BMEPxrpm(for a given displacement)
That's a nice looking car, buy a Subaru monster and autocross it.

+1 for this and for Kent's weight reduction. I think you can go to 3.4 without any case mods.

Axvel,

Here is a great thread on a build up of a 3.2L to 3.5L. This one is twin plug version. I have tried to find the thread that talked about a single plug build, no luck. Lot of good information.
http://forums.pelicanparts.com/porsche-911-technical-forum/181728-3-2-3-5l-its-finally-started.html

Have you driven a 930? The turbo lag is really bad and the 4 speed has very long gears. If you are looking for autocross performance it's not the right package. You would be better off building your engine into a 3.4 or 3.5 as mentioned by others.

Believe the 3.5liter combustion chamber's too wide to effectively fire with a single off center plug.

Axvel, if your engine's still in the car, I'd drive it for a little while longer and make careful note of its oil consumption. With a cat bypass in place, seeing a little smoke shouldn't of itself be a cause for alarm. OTOH, under 500 miles per quart of oil would clarify that a top end rebuild is in order. Once you have a sense of the current state of your engine, you can proceed accordingly.

I personally agree with others' comments on the turbo issue -- I prefer the immediate linear pickup of a non-turbo engine. Also, to your point on the 3.5, since it IS pushing the limits on spacing a bit, limiting a turbo to 3.4 would make sense. However, if you do decide to go n/a, there's a significant displacement between the (just under) 3.4l and (just over 3.5l) --

Thanks Cory, no i never drove a 930, but i do know about turbo lag.

Hi, yes the engine is still in the car, and I saw a set of 3.2 P/C's from our host is $3600 as opposed to $5600 for 3.4 P/C's.

But i was told that just doing 3.4 single plug is not enough, it is better to do twin plug 3.4.

I will check it out, i was told to go twin plug 3.4 too

hi, thanks for your input. I was gutting my car off carpets, A/C and more insulation, and radio delete.
I know find myself putting insulation, A/C and carpets back in. :) So besides that i have a turbo tail that weighs a ton, but if i remove that it will kill the look.

lots of dyno charts here if you want to get an idea of what the different configurations put down:

911Chips - Porsche Dyno Runs

+1 and who would want "low boost"

Low boost as in 300hp and 300lbft tq. And safely made not highly strung.

Which engine to choose Poll
 

Agree with this. Even with a twin scroll ball bearing turbo this would not do well on the autocross course. The turbo motor is somewhat gutless in the lower rpm range when off boost. I would choose option 4 with the more economical p&c rebuild and enjoy the car as is - especially since you've already seen good power numbers.

I would then rationalize that I saved $27k over the larger displacement turbo option and start looking for a 996 GT3. Don't get hung up on the headlights, it has no IMS bearing problems and is a very rewarding drive. Many prefer the 996-3 to the 997-3 because the handling is purer without any electronic nannies. If you sell the 930 brakes, you're half way there...

I missed this post. Plus forgetting that your looking for autocross. Turbos are hard to autocross. I too think your rebuild the current engine and using the 915 short ratios is tour best bet. Get more displacement with the rebuild. You'll be happy.