A pull corded AFFF (Aqueous film forming foam) to FIA standards is fairly good, however, double up on the pins that secure the pull cord to the bottle and regularily grease the pull cord. I pulled an extinguisher last week and with the adreniline etc it just pulled the cord straight through the securing pins!
I also can't recomend enough a 1.75 AFFF (2.4 AFFF if you have the space/cash) mounted below the passenger thighs as a good initial knock down in a fuel fire. The reason why I say below the passenger is as the driver has pedals etc by there feet so having it below the drivers thighs is minimulising the passenger cell area to extricate a casualty from the vehicle should you bin it. Also worth recomending bolting it in with 8mm bolts, as per MSA blue book regs, it's a heavy piece of kit that'll fly everywhere in a crash. If you do have a fuel fire AFFF is designed to be "floated" onto the fire from above, not aimed at it spraying the fuel everywhere.
A basic Halfords dry powder is a pretty good bet too, it can be used in an electrical fire without damaging wiring (although it will still make a mess) and dry powder is great at putting out a fire, it just doesn't have any cooling properties so re-ignition my occur unless it's backed up with water or foam soon after. The first thing I do when approaching an RTC (Road Traffic Collision) is place a Dry powder (9 litre though) to the front on the car.
An interesting point to bear in mind is only 2.39% of RTC's involve fire (Source:- LM Watson, RTC Trapped Publication) so a car fire is rare occurence now with modern cars, that said I have extinguishers in every vehicle I own.
To summerise it's all down to cash, if you're gonna compete then obviously you've gotta stick to the regs however in a road car go for small dry powder first, then hand held AFFF and then a plumbed in system. The advantage to the hand held AFFF is you can obviously aim it at the fire whereas a plumbed in system is fairly restrcted to engine bay only.
This is what I've just bought for my TVR, what would I know though!lol.
http://www.demon-tweaks.co.uk/produc...code=OMPCAB320
Cheers,
Andy