Well that depends. the biggest benfit from a set of roller rockers are more accurate ratio's vs. the stock rockers. the added benefits are reduced friction and side loads on the valve. As far as the 1.7 vs. 1.6 thing that depends on how well the heads flow. as an example. I believe the stock HO cam has a lift of .444 (with a 1.6). So the lobe lift is 0.2775.
0.2775 x 1.6 = .444
0.2775 x 1.7 = .472
0.2775 x 1.73 = .480
Stock E7TE heads zonk out at .500 lift, so yeah they are worth some power simply due to the fact there is still some flow left in the heads and at the very least you pass the .444 flow mark twice as the valve opens and closes (rather than once with a 1.6 rocker). the flip side of higher rocker arm ratio's. they increase the amount of load on lifter and decrease the RPM potential of the motor. I wanna say that on a brand X motor going from a 1.5 to a 1.6 lowers peak rpm by 300 (as a rule of thumb)
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