Hey all,

Just wondering if dual exhaust on a 305TBI powered 1989 Sierra would be a worth while investement? If so how big should I go per side. I am not sure whats on there now thinking about 2.5" coming out the back of the stock setup which is a 2 into 1 configuration.

Also...anyone know the specs of the 305TBI in these trucks. My transam has the 305TBI in it and its sitting at 170HP, 255lbs tq. I figured a truck engine would be built to have more torque rather then horsepower but I can't seem to find any information on this engine in a truck configuration.

 

I'm not sure but I know they are pretty enemic(did I spell that right?). Camaro magazine did a build up of one a few months ago now and managed to squeeze a good bit of power out of it though! I think all they did was swap cams, heads, upgraded the fuel delivery,and bored the cylinders .030 over I think. They got like 400HP out of it if I'm not mistaken.

In any event, what I'd do is just replace the factory muffler with a single in/ dual out Flowmaster muffler, then run 2.5 inch piping out the back. That is what pretty much everybody does and it works fine. Probably would be a good compliment to it to install a K&N air filter as well. Good luck!

 

ah ok. I will look into that but it looks like the 305ci is pretty much toast. Its gonna need a rebuild so I think I might just pull it and replace with a 350tbi engine instead. 305 is burning alot of oil. Might be something simple liek a head rebuild however my mechanic begs to differ. He believes its the rings.