spl questions

hello, i've got a 95 neon with a pair of MTX 8000  12" subs running off a kenwood x401 amp, last year i was at a db drag event and i hit 140.4 with my old panasonic cd player (dfx-77 i beleive) with 1.8 volt pre outs, i've since upgraded to a clarion 745mp unit with 4 volt pre outs and better s/n ratio and all that good stuff witha new cd player.

so i went to a db drag event this past weekend thinking i'm going to do 140+ based on last eyars number (i mean.,...can't drop in spl by upgradeing to a better HU..right?) well..the numbers came up and i droped to 136.4db's . nothing in my stereo has changed, except the cd player.  the only difference is they were using the pressure pads instead of the mic's and the weather was muggy and damp. would those two things cause me to drop that bad in spl or something else going on

i also check'd all the voltage going to the amps and everything....my ego go shot...i got beat by a buddie of mine with a pair of aicent old kenwood 10's (the old blue come with black dust caps)

well..the pads i feel were alot of the prob, not sure what spl they are rated for but i found out the next day no one hit over 145db's (one guy had 2 RF T2 15 inch subs in a large ported box with a huge amp in the back seat of a newer sunfire) as for the charging system, upgraded stock style battery (better reserve and CCA's) upgraded all power and ground wires to 4ga, but other then that, all stock charging system, I was however getting 13.7 with the engine running and it would drop to low 12 volt with the system cranked. the subs were in the same location. facing the back and where i mounted them befor :)   as for the placing of the pad. the ppl running the show put them in, about half way down the windsheild on the passenger side.

as for the ported box, i like the sound of those subs in the box there in, (1.1 cu/ft) they give me good punch but loud when i want loud. (subs are forsale if anyones interested) replaceing them with a pair of digital design 12's.