ET vs. MPH

I was looking at my ET/MPH compared to others and noticed that my MPH seems low. This is my latest slip:
RT .745
60ft 2.129
330ft 6.076
1/8 et 9.417
1/8 mph 72.94
1000ft 12.344
1/4 et 14.84
1/4 mph 90.14

I do feel it could do slightly better with a better launch. My mods are:

1 5/8 shorties
UD Pullies
4:10's
B&M 3000 stall (waste of money)
timing 14*
JMS custom chip
2.5" off road H-pipe w/flow master and 3"dumps (lost low end)
BFG DR's
No smog
- 25 lb. weight
removed jute from trunk and back

I was wondering if anyone else thought my MPH looked low? Is this good because I am hooking up better than others. My launch was with tires warm mashing it from a dead dig. I was thinking about launching at about 2000 - 2500 next time at the track. In the past I was getting a lot of tire spin without warming the tires. Also I lost a lot of low end when I did my exhaust (60ft. got slower but ET stayed the same) do you think if I put tail pipes back on it would make a difference?

Thanks for the ideas. I'm not sure what the track elevation is but I run at Milan Dragway in Milan Migan (near Detroit) I assume about 900 ft. I was having a lot of problems without the chip and could only get a best of 15.1 due to hitting rev. limiter. Chip is set to shift at 5200 and so far my best pass is allowing the computer to shift. Exhasust was done before the chip and I definately lost 60' when I did the exhaust but ET remained the same (made up time at the top end). I like the dumps but I am getting anoyed at how loud it is and if I could gain my 60' back by adding the tail pipes it may be a win - win. I will be doing a few additional mods soon (about $1000 worth) but haven't finalized plans yet. Most likely an intake will be in the plans.