Originally Posted by vaujot

I am obviously not Garth but based on my experience in a coupé, I wouldn't recommend M030 springs with HD shocks in a convertible. For a cab with very occasional autocross on street tires I'd go with M033 springs. Based on what I've read, I'd try the Koni FSDs with those.

Originally Posted by Lee from Koni

Since the KONI Sports for your car are externally adjustable for rebound damping all the way around, they are easily compatible with about any sane, streetable or light track duty springs. Typically the higher the rates are, the more rebound damping is needed to control the motion. Since the KONI’s adjustment range is 100% (twice as firm at max setting as it is at min setting), then you have a huge range to work within. We develop our shocks to be installed at the full soft setting to give the performance handling and ride quality that our engineers feels is the best balance with stock springs as a baseline, then you have the complete adjustment range up from there to work from. I know that the dampers were originally developed by KONI in Holland but I do not know if there was a specific package on the car beyond stock.

So long as you select a spring that comes from a company with a good reputation for quality in design, engineering, and manufacturing (Porsche, Eibach, H&R, etc.) then you will be just fine matching up the KONI Sports with them. A non-adjustable damper has a much, much more narrow window of spring compatibility because you can’t tune it to your preferences for damping, ride quality, handling and dynamic balance. We have strong relationships with most of the leading spring companies and I would not have any qualms putting KONI Sports with them so long as they meet your own preference for the amount of lowering and firmness that you are looking for.

If the car is going to be primarily street driven, I do tend to lean toward a more conservative spring rate and lowering since you need to be happy living with it on the street and it will be fine for light track use. A more aggressive track set-up may be great on a very smooth track in controlled circumstances but may be too harsh or too low for day-in day-out street use. I have never owned a Porsche myself (yet!) but I’d think that any of Porsche’s own OEM suspension packages like M030 will probably rank strongly on the slightly conservative but solid engineering and performance range so I doubt that you will go wrong there again if the lowering fits your goals.

Jason at Paragon Products is very knowledgable and helpful on Porsche stuff. He has been my go-to guy for all things Porsche for all of my 15 years at KONI. In fact, KONI gave him an award several years ago for his highly regarded knowledge and customer service. I trust his input and also have bent his ear a few times when I have begun to wonder about picking up a 993 or 996 myself. I send a lot of Porsche people to him even if it is not related to suspension.

I hope this answers your questions. The answer is “any well engineered, good quality, sane spring system within your target ride height range” should be just fine with the KONI Sports since you can tune the dampers to meet your preferences.