Disclaimer – I am not an official of the ECTA and I do not have direct knowledge of how and why the rules for ECTA are setup.
That said let me put in my 25cents worth on this.
I think that stretching the upper limits on allowable speed for cars that lack the required safety equipment is not good for the sport in general and certainly bad for anyone that suffers injuries in the process.
I don’t know where the 135mph rule at Maxton came from. I am only guessing. But there is precedence in the sport for this rule. If you go to the USFRA web page you can link to the rule for the 130mph club competition at Bonneville held during the annual World of Speed event. Or just click here
http://www.saltflats.com/I30_Club_2009.html Those rules have an upper limit of 139.999. Maxton has a limit of 135mph for similar cars. To allow for speedometer/tach accuracy you can bump that by 5 mph. So running under 140 will keep you from getting kicked out of the event at Maxton.
I am fortunate to hold an ECTA record and I did it in a car that met only the 135 or less mph rules for safety equipment. All I had was a long sleeve shirt, Snell Helmet and stock three point belt, stock seat, no air bags, no cage. 126mph in a 1994 Suzuki Swift.
I have since sold the car and am building a car that will be running slower than 135mph. My plan was to race it with the stock interior and safety equipment. But i have re-evaluated the whole deal and even though it would be permissable to run without it I plan to fully equip it with cage/fire system/racing seat etc even though the car will only run in the 90-110mph range.
Your proposed F Production car obviously has more crash protection from the factory than my car did. However, where do we draw the line?
If you want to race the car and don’t want to add the needed LSR safety equipment then I suggest you look at other venues like Drag Racing Brackets, AutoX, Roadracing Track Days etc where you might be able to enter without the extra equipment.
I respectfully wish you good luck and with your effort whatever you decide.