I have owned both so I think I can speak with some authority. I had a MK11 SPF with a roush 427 and still own a CAV with a 347. In terms of quaility, about equal. The CAV seems to be more solid to me and may be the result of thicker fiberglass, the doors shut more soundly and seem to fit much better with no air or water leakage, the SPF leaked like crazy despit me plugging all the holes I could find ( this is largely due to the original design of the MONO, but my doors never fit even close. This also translated into a noisy and heat filled cabin in the SPF. I love the hinged front clam shell on the CAV and hated the design of the front on the SPF and it is a pain to remove, but again this is the price you pay for originality. Suspension- the SPF is a superb design with great quaility, my older CAV is not as good but the newer models improve this. The cabin seemed much more roomy in the CAV except in leg room, the CAV is a more easy to live with interior no doubt, but I am only 5-8 so room was no issue with either. My MONO in the SPF started to rust very quickly, the SS MONO of the CAV has no such issues. There are several issues with the SPF cars that are slowly being worked out, mostly by owners here on the forum. I also prefer the power brakes on the CAV, but the SPF had better components. In the end, I had a SPF Daytonas( the easiest to drve daily) the MK11 and the CAV. I kept the CAV. I would however buy a SPF car again, especially if I could buy one with the kinks already worked out. One thing for sure, there is not night and day difference between the two. chuck