I just put a set of OBX Longtubes on the truck that came with a y-pipe. I had the "y" cut off the end and feed the two pipes into a 2.5 dual-in dual out magnaflow-x flow through muffler. The truck feels like it has lost all power! Did I make the right decision with making the exhaust so "free" or should do something to get some back pressure back. I plan on having it tuned but will it really make that big of difference?

 

the tuning will help alot.

 

Dam man you are making 20 less hp than me and I have a Magnacharger. What am i doing wrong? Could it be sensing Knock?

 

What PSI are you running? Stock cam?

 

Stock internals. ~7 psi. Do 1.75 1.8 or 1.85 Roller rockers work well on theses trucks?

 

Someone will likely correct me, but boost is related to backpressure.
You just make a big change in backpressure so ..pulley down
tune for the change as well

 

tune IMO

 

get rid of that muffler and get you two stait through types and an x pipe. I just switched to a tru dual 3" set-up with x pipe and borla xr-1 mufflers and it kicks ***.

 

Cam, straight-thru muffs, and tune tune tune.

 

You will most likely see a drop in boost PSI, but you will be making more power with less boost. So you can either leave it how it is and be happy with more power/less boost, or you can do like allgonoshow said and pulley down for even more power.