Shorty headers

Ironmn715 · 12-12-2012, 10:40 PM

So in my quest to come up with an exhaust for my 04 M6 LS1 I have been doing a lot of research.

My goals are pretty meager I think. I want to put down 350+ WHP/TQ. So I figure with drivetrain loss etc...that means I am looking to add in about 50-70HP to the motor using the formula WHP/.85=Base HP.

350WHP/.85=411HP at the motor.

In keeping this as a DD I want to/have to keep all of my emissions related equipment such as cats and 02 sensors.

I am torn between LT headers and shorty headers. I like the idea of the far easier install and no need to buy new mid pipes. So overall the shorty headers are less expensive to purchase, require less work to install, and no "hidden" costs with having to purchase/fab new mid pipes. BUT it would seem that the concensus is you gain MUCH more from LT than from shorties. I feel like for the cost of LTs and catted mids I could get shorties and an OTRCAI and more than likely still have a few dollars to spend on a few tasty IPAs.

Anyone out here in goat land have any thoughts knowing my intended power gains? I feel like shorties are the way to go and I can invest the money saved into other areas.

Thanks for your information fellas.

'Moe

jpalamar · 12-13-2012, 07:43 AM

Kooks SS Long tubes(coated) with catted mids, SvedeSpeed OTRCAI, and a tune and your about where you want to be.

Also, a good shifter will make your car faster in the long run then the majority of bolt ons.

BWinc · 12-13-2012, 09:23 AM

If you won't get dinged on state inspections for LTs go for it. You don't have to pay premium $$ on LTs. Get a set of JBAs and catless mids.

Ironmn715 · 12-13-2012, 12:15 PM

The problem is I have a bi yearly inspection on emission. Currently they just hook up a scan tool to your OBDII and do a visual safety on everything else. A check engine light is a failure for isntance. I don't recall if they actually open the hood and check the engine bay or if they visually inspect your car to verify if cats are in place.

I guess my question is if I were to go with shorty headers, for the aforementioned reasons, knowing the power gains I am looking for are shorty headers worth the $500ish investment or can the stock manifolds handle what I am looking to make?

I figure the cost to add that HP looks like this:

Shorty headers (JBA) $500
$40 for gaskets
OTRCAI $400
Custom cat back(similar to what Svede has recently outlined) $650+/- $50
80mm TB $400
Tune $500 +/- $100
-----------------------
$2500 total

If I made 60 WHP that roughly breaks down to $41.67 a HP.

I guess I am not sure whats the best path here. Due to emissions reasons and cost(less about the cost) I feel like shorty headers are my best choice based on circumstances.

I wonder if heads and a tune would not yeild the same power for slightly less money?

'Moe

So for roughly

BWinc · 12-13-2012, 01:00 PM

You can have the rear O2 sensors turned off, hence no codes for a reader. If they visually inspect for cats, that's different.

If you're sticking with shorty headers then you'd better change out the mid-pipes. Its in the mids where you're not realizing full HP. Changing out the manifolds will mostly get you a weight savings as opposed to HP gains. And thus you're near $1k again.

You can look at ebay and get Chinese copies for much cheaper both LTs and shorties.

Ironmn715 · 12-13-2012, 01:18 PM

So the "bottleneck" is in the mid pipes? Interesting. So would I be better off replacing the mid pipes with something with a high flow cat and NOT doing headers?

I put a set of Gibson headers on my 96 Dodge Ram Charger and I did not really notice any huge power gains in my butt dyno. Granted I alread had a CAI, really farcking loud cat back with a FM 40 Deltaflow that D R O N E D. So this experience leads me to wonder if shorty headers are worth the investment and if power could not be gained elsewhere in the exhaust system. i.e The mids on back.

'Moe

BWinc · 12-13-2012, 05:19 PM

The mids are the bottleneck. If you want HP and good sound without breaking the bank I suggest getting JBA LTs, the cat less mids and a set of thunderbolt cats from ebay. Have the shop weld the cats on. If you want to keep it simple, get OBX from ebay. Keep the exhaust stock at first. The stock '04 exhaust is killer in my opinion.

*Call* Maryland Speed and see what deals they will give you. I'm sure they can work with you.

FNG69 · 12-13-2012, 06:39 PM

I went with the JBA shortys & I'm very happy. I have a 04 also. Have 05 SLP LM exhaust with X pipe. Took me & a buddy about 6 hours to put the headers on and that's with the beer run. Still have the orginal cats on. Making 338 HP on the DYNO. Have a buddy with a stock 05 and my DYNO #s were better than his. My engine is stock except for the K& N.. Think with the goal you are looking for you would be happy with the shortys...Les

Ironmn715 · 12-13-2012, 06:45 PM

So JBA LT headers with catted mids is about $1000(headers, catted mids, gaskets, plug wires etc..) if I order it all in one shot. Which I can do but my wife will turn me into a capon.

My problem is it seems I can not do LT headers in phases. Like the Headers then the mids etc... to spread the cost out so it does not hurt the bank as much and possible fly it under the radar.

Is it possible to replace the mids without doing the headers? Then do the headers at a later date? Or vice versa?

The 04 exhaust is pretty decent for a stock exhaust. I wish it had a bit more tone. I am contemplating just swapping out the mufflers with a Borla Pro XS 2.25" muffler or something from the boys at MRT. Their mufflers are some of the nicest drone free mufflers. They do not advertise their mufflers on their site. If you call/email you can purchase any of their mufflers from the systems they offer. I am thinking the Version 2 muffler from their 2011-13 Mustang GT interceptor system.

'Moe

BWinc · 12-13-2012, 08:21 PM

Yup. JBA mids are plug and play with the stock manifolds.

Throwing this out for consideration and I won't pester anymore. I know where you're coming from because I'm thrifty. Don't look at list price. Call the vendor and ask for best price. And to cut a corner get the non-catted mid and have thunderbolt cats welded on (JBA rep himself threw that out). You might find yourself able swing it.

FWIW - While you don't have to, a tune to optimize the mod is recommended either way go.