I just built my 383 short block and I have my TES to put back in with the car.
1) Do you guys think the 383 will be able to breathe through these?
2)Are the SLP's bigger?
3)Will the SLP's make a difference?
4)If not but if I need bigger who makes them? Thanks as always guys

 

You'd want 1 3/4 TES, SLP is much better, but be sure to get the 1 3/4 kind. However, would shelling out that much money to switch from headers you already have, will it be worth it, I'm not sure. I'd try and sell the TES if you could, if not maybe try them out to see how you think they are. Obviously the car will breathe better with any type of headers.

 

I'd go with some hooker long tubes or something along that order. Why? SLP's have weeny 2.2" collectors. I was about to buy the SLP headers when i found this fact out, and along with the fact that i was already skeptical about dumping 500 into headers, i got hooker headers instead.

 

I bought the EDL 6872 from Summit but can't remember the diameter of them. Any clue?

 

In HotRod's build-up of the GMPP 383HT they used Hedmann "Step" headers that step-up TO 1 5/8" FROM something like 1 1/2" and still made 400hp and 500tq. I'm sure someone will correct me if I'm wrong on those numbers, but that's what I recall. I have replaced 1 5/8" headers with 1 3/4" Super Comps on the 383 in my Vette and there was a noticeable loss in low-end torque.

 

Edelcrock doesnt make 1 3/4" TES headers, only 1 5/8". And they used to be 1 1/2". They just switched in the last year or so.

The SLP 1 3/4" headers are the best smog legal headers on the market. Just make your own 2.5" y-pipe like I did for mine and my son's car.

If you dont have to pass smog, long tube headers are the best.