dont waste 300+ on the meter! like other have said the 3.5 inch sensore flows more than enough. i hvae a screenless ls1 sensor with 4" billet ends. it idles pretty good to me.
i got mine from Ramchargers ($119)but they said it was their last set and dint know when more would be in. i bought them so i could run a 4" maf pipe to match my t-66's 4" inlet and big mouth cold air intake.