You have to find out what will help you're set-up, some parts help and some parts hurt. when I started on my set-up I installed a Granetelli mas air and a different exhaust and it cost me big horsepower. After finding parts that did work together the tuner then makes the difference. It is possible that you're engine does not like the exhaust that you made, Modular engines do like a little back pressure.
A second thing is although you are not making huge HP gains you should also be making some 1/4 mile comparisons, as dino numbers are not a full representation of the trucks power. It may be much faster now especially with the nice torque gains that you were able to get from the mid range. In normal operation that is the RPM band that you are using, not the top end.

 

I thought about the exhaust, but since I have decreased the pulley size, my reasoning was, all that air needed to get out more quickly. After I installed the headers, I noticed a significant increase in my mid-range. My orginal plan was to have three mufflers, one with the built in x-pipe, then two more to quiet it down some, but I liked the sound so much I left it that way. I'm really thinking the tranny is my biggest obstacle. I've had a converter shudder since day one, and my original stock dyno numbers were 205/221. That's a 95hp drivetrain loss. I'm talking to Factory Tech now about at least a new converter and c-plate, but may go with a new monster box before it's all said and done. I would like to take it to the track just to get some hard numbers. According to a calculator, at 6000lbs and 408rwhp, it said I should run high 13's. I'm not expecting that at all. I know those calculators don't factor in all the different variables.

 

McDover, the problem you have now happened to me on the past.
What happened is that you lost a lot of boost when you install LT headers and the low restriction catback even adding the smaller pulley.
Get the 2" 7/8 pulley and you will see better gains.
The stock transmission can handle a lot more than you expect. I changed mine because i will make a lot more than 500RWHP. You didn't need the BAP, the stock pump is good for 500RWHP but as you stated, you are ready for future upgrades.
What headers did you install ? Did you customize them to 8X2 ? The 8X1 headers must be choking a lot of HP on your engine. Your truck is making real nice HP and TQ now and it deservers 8X2 headers. For less than $1000, it can be done.
Congratulations for the numbers, and the 30-40HP extra you are missing can be achieved just with the header work.

 

My headers are the same as yours, Dynatech LT's. The only difference is I had them ceramic-coated at Jet-Hot. I modded them to 8x2 into a di/do magnaflow muffler with the built in x-pipe. I had the exhaust work all finished before I went from the 3.375" pulley to the 3.0", so I don't think it's the exhaust. I'm pushing 9.5lbs of boost with this pulley.

 

Do you have a pressure gauge in the truck ?
Do you have pictures of the custom headers work ?

 

you said you feel a big gain, then why are you so worked up over what it says on paper. There are tons of factors involved, unless the dyno runs are dont back to back, and you do more then three then you can never know if that was an accurate reading. Hell even tire PSI could mean some powertrain loss.....

when my roomate had his camaro on the dyno for tuning, he had about a dozen runs before they knew they had everything perfect.
-Patrick

 

I have a boost guage. I'll take some pics today of the exhaust.

 

Did you get the 4.56 gears ?

 

What? I felt a big gain when I swapped the pulley. Dyno showed a lean condition with the stock injectors, so I swapped them out for the 39# Cobras. Went back to the dyno cause a tune from scratch had to be written. I picked up 4 peak hp and I DO NOT FEEL ANY GAINS WHAT SO EVER FROM THE NEW INJECTORS AND TUNE. I understand the effects of consistentcy from dyno runs, but if I had more significant gains than what's on paper, I would/should notice the difference. That tells me the numbers are pretty dead on. Nobody would "feel" and extra 4hp.

 

Nope. Got the 3.73's that came on the truck. Since I do a good bit of highway driving, I couldn't justify going up in gear and getting worse mileage than I do now.

 

Do you know what's your tires overall height ?

 

I'm with LowFast on this one. Lean tunes make the most power but are not safe. You now have a safe tune.

The new injectors and pump increased fuel flow for a safer tune, but didn't do anything to alter the airflow characteristics of your setup...so no significant change in power.

The rest of your setup looks good on paper. But things like a pulley change, exhaust work...the best way to see what works best for your setup is to make one change, log the results, then make another change. If you change several things at once, you can't tell if what gave you a gain and what potentially lost power.

Who knows...maybe the pulley was worth 40hp, but the exhaust lost 30hp...just speculation, but you have no way of knowing.

Good luck

 

Did you're tuner data log timing? Depending on other factors the timing may need to be changed. Other factors in the tune can change commanded timing and air fuel adjustments. You're air/fuels are where they should be that is evident by the wide band graph, but the computer could be pulling timing because of other factors. If timing was not logged I would see what it is actually doing.
As far as ET for a 6000# truck with 408 HP at the rear wheels My calculator predicts a 14.35 et at 95.89 mph. That's not shabby for 6000# with little aerodynamics.

 

What do you think about upgrading to a 95mm MAF? Other than doing some tranny work and maybe freeing up some of that massive drivetrain loss, any more suggestions?

 

I'm sure he did. I'll call him tomorrow and check.