11MPG

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?

TXsilverado

iTrader: (19)

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.

11MPG

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.

madmann26

iTrader: (7)

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.

bigsapper

iTrader: (2)

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

RacinRust

See Road Kill Exhaust Header Bash.

Uppgrade

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.