I have a set of the SLP 1st design runners which are the ones that have 1 pair of runners siamesed like 1.5 to 2 inches in on both sides, while the other pair of runners is fully siamesed all the way down to the intake manifold. I was planning on putting this on my new to me 87 GTA along with an Accel TPI intake manifold base. I know most folks are familiar with the 2nd design which has both pairs of runners siamesed in like 1.5 to 2 inches on each side. There's pretty limited information on the first design SLP runners anywhere. Does anybody run these? Any ill effects? I'm wondering if this creates some sort of imbalance between two pairs of chambers on each side of the engine? Does anybody know when and why SLP changed designs?

 

The casting is bad the ports arent a circle alot of the sets Ive seen the part that bolts to the base is really thin and mismatched leaving very little room for the gasket to seal, the one pair of runners that has no divider imo shrouds the new port entry which is now the base maybe this is why slp went to the second design. They do have the bolt bosses in different configuration that doesn't make them protrude much inside. There a novelty because of how many there are out there and because many thought thats how all SLP runners where that they were empty and siamiesed inside

 

The 1st design look like they were made by a junior high school for a casting project. New supplier, updated design. More running changes to their product line.
they need a lot more work than the 2nd design to make them do what they need to.
i have a few sets of them and they run fine but need work for good gains