Like Title states, I currentley run a pair of the trickflow twisted wedge heads part # tfs-51400004 they are the 170cc track heat heads with 61cc chamber, they are slightly hand ported and gasket matched to lower intake with ed curtis valve springs and a valve job. I was wondering whats the best cc heads on a all motor 306 c.i h/c/i full bolt on cars, I currentley run those heads with a ported trickflow track heat intake with 75mm tb full exaust long tubes, comp cams xe274hr extreme energy cam, It makes power all the way to the 6200rpm cut off, my ? is I was thinking of selling my trickflow heads to upgrade to a new set trickflow has out they have a pair of 185cc heads and 190cc heads guys seem to say they are a ton better? my ? is what cc head should I run my current compressions is 10 to 1 I want to keep it around the same so these are the 2 heads im thinking of buying to replace my heads with they have diff cc size so didnt know what was ideal for a n/a all motor 306 car. my current head is this below trickflow tw 170cc (track heat head version of this ) link: http://www.summitracing.com/parts/tfs-51400004-m61/overview/ to upgrade to this 185cc head 64-66cc link: http://www.summitracing.com/parts/tfs-51410004-c01/overview/make/ford http://www.summitracing.com/parts/tfs-5261t661-c02/overview/make/ford or to upgrade this 190cc 56-66cc link: http://www.summitracing.com/parts/tfs-5261t561-c02/overview/make/ford or upgrade to a pair of the new "high port"fast as cast cnc 192cc heads link: http://www.summitracing.com/parts/tfs-51700001-m64/overview/make/ford I've read tests they show a 30-40 hp gain through out the power band esp on the top end for the 185-190cc heads over a 170cc head.