i think they are referring to stock.. or they may be referring to the fact that if you swap heads and intake as they also reccomend, you should switch to bigger injectors which require a different mass air calibration.
TFS#1 appears to have a nice aggressive ramp rate. Advertised duration @ .006" is only 275/279 while dur @ .050" is 221/225. Not bad. This is comparable to some of the CompCam Xtreme lobes. Well, at least its alol closer in ramp rate to the Xtreme line than to FMS's ancient cams - LOL!
BTW - The TFS#1is a good cam for a 302ci/306ci IMHO.
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