Truck has only a 5.3 but lots of flow potential. TBSS intake with 87 mm throttle body, Trick Flow GenX 205 Heads and a 226/236 cam. 3,200 rpm stall and 4.88 gears with a 33 inch tire.

Thing is I sold some rusty headers I had and currently have the stock manifolds back on. Getting the Speed Engineering true dual 3 inch when it comes out, and I'm considering their 1&7/8 headers. Getting the truck dyno tuned again after the new exhaust get's installed.

Question is, am I shooting myself in the foot somehow getting the 1&7/8 headers vs the 1&3/4 headers?

 

Only way to truely tell is to get it on the dyno. 1 7/8 with. Dual 3" sounds like overkill to me on a 5.3, but thats just an opinion...ive never had the combo back to back on a dyno.

I say go for 1 7/8 dual because if it does hurt, it wont be a crazy number but will give room to grow if you ever step up to a 5.7+ CI combo.

 

That's what I figured. Some people rant and rave against big pipes but no one has a clear cut answer. Also most don't retune and just go by "butt-dyno." It'll be neat to see cause my tuner still has my old graph of 1&3/4, 3 inch Y-Pipe to muffler to dual 2.5. When Speed Engineering releases their kit I'll post and overlay of what happens after the tune.

 

Small(er) motors and big headers add up to one thing = it hurts scavenging.

Scavenging is needed at low rpms to help with hp/tq production. Once you go boosted, things change a little.

If this were a 6.2 motor, then sure, 1 7/8 would be the way to go. For a 5.3, I think you'll hurt your low end.

 

I've got 1 7/8 Kooks on an otherwise stock 5.3. It does not lack for bottom end.

 

See Road Kill Exhaust Header Bash.

 

You're not bone stock. With your current combo I cant imagine you not being happy with the power and torque from the 1 7/8. But have to try and see.