First off, it's not the battery.

I can only keep enough juice to barely start the car. I can get it started every time, but it cranks SLOW. My EGT gauge also suffers sometimes from low voltage.

I'm pulling a lot of juice. Lot of gauges, fuel pump, 2000W audio/video system, alarm/remote start. I do have a capacitor... and an Optima yellow top battery. I have thick solid grounds.

I'm thinking the UDP isn't letting the alternator do its job. IS there an overdrive alternator pulley available? How about a higher current alternator?

Yes, there is a overdrive pully for the alternator. I have it. they only made them for a limited time about a year ago at a local speed shop for neons. It raised my volts from 13.4 to 14! I was pleased. I can talk to the guy to see if he would make some again. But there would probaly have to be a group buy, since these things aren't all that fun to make, I doubt he'll make just one.

Have you ever fully discharged your battery?

The alternator can't recharge a battery more than 20% or so. If you have a battery that's been discharged to 0, you'll never be charged again.

Buy a $40 trickle charger, easy to find, and charge your battery overnight.

there are overdrive alternator pulleys on the neon boards, search for demeye racing i think they had some still...
Bill

Heres a link to a great drop in alternator at a good price

http://www.4alterstart.com/pages/store/skudetail.nhtml?profile=highoutputalternators&uid=10662&catuid=10013&returnURL=http%3A//www.4alterstart.com/highoutputalternators

Honestly it sounds like it's either your alternator or your battery like stated above. I honestly doubt it is only due to the UDP. There are many of us on here running an UDP with large stereo systems. You can take your car to Autozone or Advance Auto and they will test both your battery and your alternator for free.

I say alternator or battery. BUtyesthey make an overdrive pulley, it's the same as an underdrive alternator pulley when used with a Underdrive Crank Pulley. It restores the ratio between the crank and alternator pulleys for the speed it psins the alternator.

I have one, it's nice, and lifghter than the stock one too.



15.9 @ 86.7mph

Smooth idle? We don't need no stinking smooth idle.

Mods List:
http://highlander.dsmpower.com/sig.htm

yeah, i run just as much electrical stuff as you do doug, and I have no probs. My setup is just like yours- yellow top, udp, and stock alternator. I'd bet your stock alt is starting to give out. I replaced my stock one with a Duralast Gold alt, from Autozone, and never have had an issue with it or hard starts. If the yellow top is making you start hard, then its not being charged properly. Our alternators will be able to put its full 90 amp output at rmps above 1000 or so. The only way you would be able to drain the batt with the udp, is to let the car idle for a very long time, and have a really good amount of current draw from all your electircal devices. I suggest to not let the car idle for very long with larger current draws, as that can prematurely damage the alternator.