Truck lags can't figure out why. Need help.

[sanattof]

Here we go. I have a 2000 1500 5.3.

This what I've done to the truck recently.

New fuel pump and filter.
Headers.
7.5 race wires and new platinum plugs.
Cut the cats and put on 2 of the old style Thrush mufflers. Now it's real dual exhaust instead of single.
Added a Powerdyne Throttle spacer.
K&N air filter.
Also have the hypertech

2 problems now.

Now without using hypertech the truck hits the rev limiter and starts bucking when you stomp on it.

And most inmportantly the truck lags now. It doesn't take off like it used to. Almost feels like it is carrying a load.

Obviously there is a lot more horsepower now then stock, so maybe no backpressure?

Any ideas would be helpful. Thanks.

[gschretter]

The engine is heading towards a blow out?

You might have worn/damaged something.

Do a compression check?

You said:
hits the rev limiter and starts bucking when you stomp on it

That is what is suppose to do right?

Was there some mig welding with the exhaust?
Did they unplug the - battery cable when they welded?

How far are the welds from the O2 sensor? Could have damged it.

[kenny-1907]

I have a 2000 silverado with the 4.8 and when i had dual exhaust installed from the cats back (cut the Y pipe and continued dual right thought with 2 dynomax turbo mufflers) I lost power. took it back to the exhaust shop and they put a crossover tube in also called a balencing tube , it just equalizes the pressure in each side, which made no differnece. Took it back to the exhaust shop about a week later (almost seemed to be getting some power back) they cut off the dynomax mufflers and installed a set of flo pros.........back to sucking on power.......drove it like that and the more i drove it the more the power came back. I would say it took at least a month or so for it get the power back and i have heard of other people having the same problem. I don't know if this is the smae thing you are expierencing or not . Just a thought