I have a similar setup as you do and have ran over 100 times in the 1/4 mile with my 240. Some of the differences i have is Megan coils they are setup with the softest setting in the front and a mid setting of stiffness in the rear. I have the mickey 255 drag radials. I also have an ecu tuned by enthalpy but, mine has a two step on it for 5700 for the lunch. I usually don't have but 1/4 to 1/8 of a tank of gas in the car. My best time which i have backed up many times are:

60' - 1.661
330 - 5.026
1/8 - 7.698
mph 92.87
1/4 - 11.944
mph 114.51

I do have a gt2871r but, if your hp numbers are right then i would think you would be able to get somewhat close to these times. One thing you might try is to look at your drag radials what tire pressure are you running? How long of a burnout do you do? I run 17 lbs. of pressure which is the lowest you should run. My burnout i get the tires wet first then i do a 2nd gear burnout for about 5 seconds. For the boost variance I would look at your vacuum lines and see if there is something going on there. Then look at the settings of the boost controller. Hope this helps out a little.