The Dyno Dip

[Matt Davis]

http://www.b15sentra.net/mdavis/albums/hosts/DYNOSEAF.jpg

Could that be what causes the  engine to do that Dip at that rpm range?

(note on the dyno above how it pulls the timing and dumps fuel at that
3500-4000 rev range.)

my modifications:
bkR6e plugs
hs header
Hs intake
2.25 exhaust.
and obviously advanced timing :D

i would lean towards the advanced timing causing the problem however Ive
noticed that on STOCK Sr's
mike kojima said:
 Note that
> past 13:1 is right on the edge of destruction and the
> motor has to be right to do this for long.

> Built NA motors can run 12.7-12.9:1 as they don't seem
> to respond as well to being tuned super lean.

> Mike