06 Silverado Shifting Problems

[formulation]

I have an '06 Silverado Ext Cab 134 inch WB 5.3L Automatic 34K miles with two mods: Gutted air filter box w/ K&N panel filter and Cat-back Flowmaster dual 2.5" outlets from Super 40 series muffler.

 

The transmission seems to take too long to shift into overdrive and lock the converter when cold. I have driven approximately 2.5 miles on the freeway (at 70 mph) before the converter locks. This is the scenario. Crank truck, drive 1.25 miles to freeway at 35-40 mph then 70 mph on freeway.

 

Anyone have any suggestions? This seems to have developed a few weeks after installing the catback system.

Thanks formulation

[formulation]

I have an '06 Silverado Ext Cab 134 inch WB 5.3L Automatic 34K miles with two mods: Gutted air filter box w/ K&N panel filter and Cat-back Flowmaster dual 2.5" outlets from Super 40 series muffler.

 

The transmission seems to take too long to shift into overdrive and lock the converter when cold.

 

 

Well, I inquired elsewhere and wsa told this is a normal situation when cold. The converter will not lock-up until the engine/trans are at a certain temp to reduce emissions.

 

Thanks anyway,