LZare

I just got my ls2 tuned with vararam corsa axlebacks and a cat delete and im pretty sure i read people saying you get more power outa headers and highflow cats rather than just going catless with stock headers... well i put down 391hp/390tq and i like the sound. Its loud when i get on it and i can barely hear it at highway speeds. i read people putting down 380ish with headers and intake. so would i lose power with headers and cats? Im just going to put the money to my vortech i think

tennblkc6

so...you putting down those numbers without long tube headers?

LZare

yeah, tuned at LMR here in houston. ill probably post the dyno sheet

LZare

tennblkc6

hmm...so basically just a cat delete and you dynoed ~50 rwhp over stock?

LZare

well vararam too.. but yeah lol. so you think headers would still help? id be afraid i get them and lose hp with cats then go catless and have it be too loud. i do find my numbers kinda funny when i see people with the fast intake and other stuff making less

SlayerRX8

Yeah that seems a bit off. Headers do tend to make more power, though.

LZare

i mean not exactly from what im reading lol probably just going to skip them until i go FI or cam because i dont know what gains i could really see right now. Am i really supposed to gain 20 more hp from headers over no cats like people said because i dont think anyone has put down 410 with headers and intake.

tennblkc6

if you add headers and stick with the same dyno you should see gains. if you go to a different dyno you will be disappointed.

LZare

nahh LMRs numbers are good but i appreciate the advice

WA 2 FST

As the others have said, you will not lose power going LTs. LMR will tell you the same thing. You'll pick up power/torque throughout the rev-range. Use the same dyno to compare gains.

Xtremespeed

It's not that LMR's numbers aren't good, it's just that different dyno's on different days or different weather can show pretty big discrepancies. It's really just a tuning aid, so to see accurate gains or losses, you need to use the same dyno in very similar weather conditions. Headers should give you some nice gains, and if you use hi-flow cats, they will keep the sound down to a decent level and not hurt the power much at all.

LZare

when people say lts will not lower hp are you meaning catted lts? because i know lts raise power. i just can't find anywhere that people with intake and catted lts make more than me. And i know dynos vary he just said if i go to a different dyno i will be disappointed and i was saying lmrs numbers are good because i doubt LMR is the highest reading dyno ever like his comment pretty much says lol... Pretty much my question is not if ill gain or lose power its if anyone with intake and catted headers has mad over 391. my buddy had a mustang dyno at his shop that reads low and I'm gunna dyno it there pretty soon for ***** and giggles.

WA 2 FST

While I completely understand your concern with spending $$ and going backwards as far as power goes, what everyone here is asking you to do is look at this a different way.

Your car made 391rwhp on LMRs dyno. That's great. In fact it is excellent. Here are two scenarios I would ask you to consider: 1) another LS2 with the same exact mods as you will also dyno very close to 391 on _that_ particular dyno and/or 2) you have a car that makes more power than most LS2s with similar mods.

_Regardless_ of the above scenarios... your car will still improve power/tq with headers and hi-flow cats installed.

While you may not find on here another car with your same mods make more power than you on a different dyno (and you will also find some with LTs and cats/deleted cats that make _less_ than you)... it is well-known that LTs with good, quality hi-flow cats make greater power than stock manifolds and an off-road X-pipe.

Given you trust LMR to tune your car, and you trust their dyno, it is as simple as asking them. Certainly they will tell you what the rest of us are telling you... that LTs and high-flows > stock manifolds + cat-delete. They probably even have dyno charts they can show you of other LS2 cars with a CAI and LTs to compare to yours...or that you can see gains over stock.

Asking here is fine and good, of course, but I'd get the opinion of the shop doing the tuning/dyno, and take that with more confidence than trying to compare here.

Just my $.02.

LZare

yeah i was just trying to see if anyone had put down more than what i had kinda curious. guess i coulda called the shop but didn't ask them when i picked the car up because i didn't know it was high this is my first ls motor. Im ordering a supercharger next week(probably vortech from what ive seen) and will most likely order the headers at the same time depending on the install price i get on the charger

brewcitygymratt

Damn you made more 13 more hp than my 06 with ported fast, ported TB, vararam, long tubes and corsa sport with carted x thru a circle d stalled A6. My car dynoed low 330's stock. You must have a factory freak.

LZare

I really don't get it lol, maybe they had done something internally to the motor, I just bought it with 34k miles

LZare

Asked this back in 2015 lol, sold the vette a couple years later for a hellcat. Funny you bump this now right before the c8 comes out while I'm sitting here debating if I trade the challenger in🤣 all depends how it looks without the camo/ if they make us wait a year for the z06 or whatever it will be called

Orion2011

More likely it's variances in dyno, weather conditions, humidity etc. Dynos do not spit out a number you can take to the bank. Like many have said use the same dyno and as close as possible weather conditions when comparing results.

Apocolipse

And use SAE correction.