240z73dats

I was thinking of wideing the ends even having a profecional cut it adn adapt a bigger line were possible. now i dont want to cut corners and kinda want to do it right ive invested 2 years and 5gs and no were near done or even looking perfect!lol but its a passion right!??? i still neeed to install coil overs or shocks not sure but should i just pay the extra cash and have the bigger return line and fule line installed?... sorry for this question maybe should of mentioned it or could be a totaly seperate issue.... well right before i did the swap the car was backfiring pretty bad... it doesnt only when i let off the peddle and coming to a stop. if im pressing the gas peddle it sound fine its when i left off the peddle that it back fires. the exhaust is custome made and have glass packs in the middle and was told by the guy who installed them that its becuaseof that i hear a back fire... ur help is very appreciated and i am welcome thank u guys

hi i am new to this forum and well i singed up cuz i need help! i have a 240 with original fule lines. i am running a L28 block with a bored and polished p90 head which was carbed but i just installed a non egr fule ingetion system which has i beleive 38mm fule injectors and 50 mm. throttle body (webber throttle body)... (i payed 500 for everything with instalation) the guy who installed it kinda just slapped it on. he mentioned the fule lines needed to be swapped to the bigger 280 fule lines which i have but kinda dont wanna spend the money to install since i rebuilt the suspencion completely... so is this a MUST for me to install the fule lines? what will happen if i dont? can i get away with the stock fule lines?