These sleeves are to fill and smooth the exhaust ports when adapting 1.5 inch headers or old style SSI heat exchangers to a 3.2 head. The standard heat exchangers have a sleeve that fills this counterbore, but when using headers without the protruding sleeve the counterbore in the head creates a discontinuity. These were used in my spec 911 race car. $39 for the set including shipping within the Con US. Outside the Con US will be $39 plus actual shipping costs.
Thanks.
