you will have to get yourself some kind of reducer mate. bob down to a plumbing shop and they should be able to sort you out as they have loads of reducers
hang on a sec though. if the efi pipe is 70mm as you say, then how can the samco we need be 45mm? the efi pipe comes off the turbo meaning that it must be 70mm then? im abit confused.
i think its the bend and size reduction that causes the efi pipe to be so restrictive so i think it may be best to ditch it all together. this is something im looking to do next so let me know how you get on lads.