SPD downpipes and lower 0-60 times

[Ford Guy]

Interesting since I put on the SPD downpipes my 0-60 times have been much worse..I know there's time the computer needs to learn with new parts and revision to the tune but I went from 4.11's to 4.28's
Anyone else experience this after a mod like dp's?
I have noticed though aside from that glorious whistle sound of the turbo spool the higher end pulls are much better. I'll be doing 70/80 on the highway and give it some throttle and its like doing a 50 roll. Real linear instant power.

 

[F=MA]

More wheelspin?

 

[Ford Guy]

More wheelspin?

Nope. I actually have had much better launches even at 2500 to 2900 rpm range and honestly it feels faster than before so I'm perplexed how its slower on the dragy.

 

[TMac]

Is is warmer outside than when you ran the faster times? More humidity? Gas or ethanol ratios from different places or not checked? You probably need a few more runs under similar circumstances to get a real average.

 

[Ford Guy]

Is is warmer outside than when you ran the faster times? More humidity? Gas or ethanol ratios from different places or not checked? You probably need a few more runs under similar circumstances to get a real average.

Also similar. The DA is similar and temps as well. I run the dragy on the same street. One difference is the tire psi. 4.28 was with 34/35 and 4.11 was 26/27 but no wheel spin with higher psi. I'm going to try some more runs tomorrow and see. I did some data logging for the tuner and the air fuel ratio, spark and knock sensor is all on par.

 

[zdubyadubya]

I would double check that you aren't getting a false knock from somewhere and its pulling the timing. I've heard of several guys having something random set that stupid sensor off.