I have a 2001 Lightning with a 2# upper, 12"filter, Magna Flow Cat back, boost by pass and a Predator.

I want to add some more boost and want to know if I should get a 2# or 4# lower and keep the 2# upper or get a stock upper and get a 4# or 6# lower. Thanks for any advise.

 

I would go with the 4# lower
If my memory serves me right you are at alltitude so your going to run richer than us sea level guys. Just make sure you get the preditor retuned for the new pulley.

 

I personally prefer the larger crank pulleys (I'm running a 4#) with the stock upper. Less slippage because the larger the upper pulley, the more surface area for grip.

It comes down to cost probably for you. You should be able to get ahold of a stock upper pulley for pretty cheap. Lower pulleys are under $200 depending on where you go.

I'd go with a 4# lower and change back to the stock uppper, IMHO.

 

i had a 4lb lower and wanted some more but could not decide if i should go for a 2lb upper and keep the 4lb or go with the 6lb lower. the thing with two pulleys is the ratio if you have a 2lb upper with a stock lower what would it be with a 4lb lower not 2lb??? i dont think so

 

The big question here seems to be how much is to much?

I live in a similar climate (dry weather) i have a 6lb lower and stock upper.
I have problems when the temp here drops below 30 degrees (foul plugs denso 22)
other wise i love the extra boost.

 

go with a 4lb lower. Take the upper of for now and when you need more boost in the future you can put it back on

 

I have the #2 upper and the #4 lower with a predator tune by Diablo, no headers, stock plugs, K&N flat filter in stock air box modified with a home made ram air system and a borla catback, boost is up to 14.5- 15 psi which is the perfect limit for a stock bottom end. The truck runs awesome with lots of torque and is probably in the mid 12's ( haven't gone to the track yet but if pulling a 2002 corvette convertable by three lengths up to 90mph is any indication then it should be in the 12's). Have not experienced any belt slippage yet, I am very happy so far. Remember a GOOD TUNE makes a difference between good and great.

 

4# lower and 2.80 upper
Denso IT 22's gapped @0.40
Good safe tune (16deg. timing)

No pinging at all even in 10deg weater.

I get 15# of boost in 25deg. weather and 13-13 1\2 in hot summer weather.

I had belt slip before the upper and after. I put on a gatorback 66" belt. NO more belt slip (i did break the tab off).

in 50 deg weather I ran a 8:12 @86 in the 1\8th. That is a solid 12.8sh in the 1\4mile.

If I had it to do over I would do a 4# and port the eaton. or maybe a 6# by itself.

all in all I am happy and no regrets.

 

Thanks for the help everybody. I will probly buy a 4# lower and get a new tune.

 

this will give you some input into your decision.

change the pulley size in the last column to figure out what works best in your situation.

http://www.msu.edu/~nawrock3/BlowerRPM.xls

(this is stock Eaton, NOT PORTED EATON)