hi ive got 6mm fuel pipe on my 1.8 pinto is this too small or will it be okay?

My understanding is that it will be ok for carbs but to restrictive for injection

my v12 jag has 8mm pipe, and it was a 5.3 litre doing 3mpg under acelleration. So, i recon 6mm is there abouts - but most fuel line I have seen is 8mm.......


atb

steve