I was questioned about my hitting 18-19psi with E/C datalogs and the couple of mods I have. It is it that unusual? Always understood these ran 14.5psi stock and the 54.7mm(65) E/C pullet gave "about" 3.5psi extra. If true and I get a 5% increase going with the 178/70 combo I would be around 20psi which i would think is just right for not wanting injectors and all. I did buy an SL55 pump, used, of ebay yesterday for $80. shipped. Seller listed the miles as 45k I believe and said it was a parts car that ran before the pump was removed. Rob's regulator and freeflow filter should round out the fuel mods and keep the SC right in it;'s sweet range, 15,000rpm. If I went to a 69mm I would gain 8% which might get me to 21psi briefly, safe or stay 70mm? I plan to visit the shop today for some lame reason. Maybe show the owner my plastic calipers covered with some sticky substance Really I want to talk about thee grooves but not sure what to tell him besides they are important.

 

Here is the SAE spec for serpentine belts.

I used it for my SL55 pulley and it worked for me

Cheers,
Chris