hey anyone have these on their car?..do u know if they're 1 5/8 primaries or 1 1/2...if they're the 1 1/2's they're probably meassuring the ID and not the OD like most companies do...and what y-pipe is everyone using w/these headers...opinions welcome...i'd really like to hear from someone who has used these...thanks

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91 Pontiac Firebird...305 TBI
black, t-tops, auto
K&N 14x3 open element flat base air cleaner, 3 inch high flow cat, 3 cat-back into a flowmaster 80 series, IAT Resistor, ultimate TBI mods, 160 stat Hypertech Thermomaster Chip, TC lock-up switch, SLP Torsen Posi w/Richmond 3.73's, removed rear seats, Spohn LCA relocation brackets...SOON TO COME...headers and y-pipe, Nitto Extreme Drag Radials, LT1 Cam, Edelbrock Performer manifold