Hi Kieran
for point 3. the 15 degree from horizontal is the best angle but anything from approximately 45 degrees is ok - I assume that you are using mounting points pretty close to where the base and back of the rear seats meet? normally that will make the angle in the region of 45 degrees which be be acceptable ( providing the mounts are reasonably strong)
IF the points need to be move it will only mean a new hole,a spreader plate and an eyebolt - although the cross bars mentioned are the best solution in a purpose built car but they will not become compulsory
As i said in a previous post , I'm not intending to go round measuring these angles - the object is to get the mounting points away from the floor immediately behind the seat. I used to compete myself so I do appreciate the problems in competing in a road-going car
point 4:
thats a very good point - i'm glad you asked me .... I will make that one clearer in the regs
If you are using a OEM system with the tank fitted below the floor with no big holes in the floor, and the boot does not contain swirl pots , pumps, filters etc then there will not be a need for a rear firewall - in other words ....
an empty boot will not need a firewall. Fuel pipes through the interior will be acceptable - but they must be either metal or braided and they must not have joints inside they passenger comprtment,
For the front , all cars will need a fire wall - but all that really means in most cases is that if there are holes in the bulkhead, bung them up using- bolts,rivets,metal plates,fibeglass,fireproof mastic etc.
marc