weird .....turned up the boost and car seems slower

[vroombout]

ran my car a while back at the track. on stock boost my car did a 14.0 @ 102mph not bad trap is pretty high and had some wheel spin so w/e

installed an AEM Tru Boost controller (electronic)
turned the boost to 12psi and ran down the strip best time was 14.7 @ 99mph which even if i had more spin which it didnt seem i did my trap was lower everytime
i then went to 15psi and did 14.4 @ 99mph
wheels spin aside it didnt feel any better and i never achieved 15psi
i did reach 12 when set to 12

only other mod since the stock track runs is a welded diff.

but even then if i turn the boost controller off i still spike to 10psi or so when its a 7lbs spring .....ideas? maybe re gapping my plugs may help my power but im still spiking

[PapaSmurf2k3]

Was the ambient temperature different?
The only thing I can think of is if you have a boost leak somewhere? Maybe your turbo is going out? Out of its efficiency range? Pistons getting tired and losing compression?
Can you turn the boost back down to stock and be faster?

[sommmatt]

Have you done any kind of tuning whatsoever?

Differences of almost a second are something you should feel on your butt dyno.

[Shadow Drifter]

Check your plugs and are you running a wideband if so what are you afr's sr's run best about 11:4.1 afr also try cleaning your MAF and air filter too