what kind of spring

[PToombs]

If I could make it stay up longer I would be better off.

Oh boy. Man oh man. I gotta go before I get myself yelled at again.

[oldestof11]

Something I thought of is to have 2 valet switches, one to limit all flow and one that has a performance setting. Lightly roll into the throttle and then once it hits the floor, presses a switch and viola! All the boost is their...

[unixcowboy]

Latest spring and results :
I ran my 13 mi test route which includes city and hiway. Actually 2 different hiways so I can set cruise to 68mph and then hit the 270* exit ramp which slows me to ~ 35mph, then I hit the resume and let the cruise accelerate back to 68mph. This way I get a feel for how the mods affect city driving and I know the hiway acceleration is pretty much the same since the CC is doing it.

New Spring
http://www.cumminsforum.com/gallery/sho ... puser/9741
This spring reaches a maximun of 35lbs pressure for full compression. This spring is actually 0.23 shorter than stock. Next spring will be a little longer and I'm shooting for a 50lb spring.

Stock spring travel - max boost reached ~ 15psi
http://www.cumminsforum.com/gallery/sho ... puser/9741
You can see where the track is past the slope and nearly at maximun extension. Some smoke but not a blackout that clears by 50 mph.

New spring travel - max boost same
http://www.cumminsforum.com/gallery/sho ... puser/9741
You'll notice the track is barely at the end of the slope. Very little smoke initially that disappears quickly.

For those who wonder about the effectiveness of a valet switch, here's a photo with the valet active - ie blocking boost from the AFC
http://www.cumminsforum.com/gallery/sho ... puser/9741
Look VERY close at the bottom of the pin, you'll see a shiny spot where the guide pin was touching the fuel pin. I had to rotate the pin a little so the spot would show up better in the pic. The pin didn't move down at all. Surprisingly I was still able to hit 15 psi boost when I got into the throttle. Virtually no smoke other than the haze I have all the time.

Haven't hit full throttle yet to see if I've lost anything on WOT. I have noticed EGT's down by ~ 100* so I'm definitley getting less fuel at the same boost and road speeds.
All these tests included a heavy blip on the throttle in town to see if I could smoke-on-demand and the answer is definitely, but different amounts from a cloud to a large puff when the valet is on.