Greetings to all.

I've read a lot of articles (namely, the threads here, as well as the exhaust articles on ws6.com, and talking to my brother, a GM mechanic who seems ungodly gifted with small blocks..) and I'd like to start a discussion on a few emissions-legal exhaust components. I asked my friend Dave (scoobysnax) this question a while ago, and I enjoyed his answer. I'd like as much insight on the topic as possible, so here goes.

WS6.com states that stock exhaust manifolds and stock y-pipe are not very free flowing at all. I beg your pardon as I am new to LT1's and this site, so please bare with me. Simply put, my question is this.

I am in an emissions area and LT's are not an option for me.. But, I was wondering if a combo of shorties, a hi-flow cat, some replacement y-pipe (perhaps random tech?) which may flow a little more freely, and a good catback (i was thinking of SLP 2OTL or loudmouth) would yield pretty much the same gain as going to an emissions-illegal LT combo. (Or at least come within 5rwhp of them). I'd like to get the most muscle I can out of my car without having to do internals (ie. cam, rockers, springs, any of that). With the exception of the pipes being somewhat narrower, and obviously shorter, would my gains be similar while I might pay a tad more for the combo?

My most profound apologies if you've read this far..but thank you.

 

I just went from a stock exhaust with borla muffler (not catback) to SLP headers and 2OTL catback. With altitude adjustment for the different weather conditions i gained .35 sec and over 3mph and runs with identical 60' times. That was with a bullet muffler ORP. I have the ORP flanged for a 3" catco. You cannot feel a difference with the cat in. It may be robbing a couple HP, but it will still be a very large gain vs the stock exhaust. The emmisions legal SLPs, AS&M and RKsport midlegth headers all perform very well.

For me it wasn't the emmisions, it was the fact that my car is lowerd. You aren't giving up that much with midlengths vs. longtubes.


-brent.

 

This combo has worked great for me and netted me a 13.09@106.82 in march:

Arizona Speed and Marine Headers
Random Technologies Catalytic Convertor
Random Technologies 3" Stainless Cat Back

With just the exhaust I gained over .5 and 5 mph in the 1/4.

The ASM headers are pricey, but the quality is outstanding. The random tech stuff is top notch, and the muffler is a straight through design, with most of the exhaust exiting on the driver side pipe.

 

I was told that the FLP Long Tube header set up from thunderracing.com will pass emissions... maybe I'm wrong? Does anyone know for sure if they do.. cuz I was planning on buying that set up soon (the LT's, Y-pipe, cats and off road tests pipes, all ceramic coated) But they have a pretty heavy price tag so I don't want to get them and fail emissions.

Trevor

 

I don't know about canada, but here's the thoughts:

They should pass the emissions test without a problem. The area where the problem lies is the visual inspection. The cats have been moved, thus causing an instant failure.

 

The AS&M headers listed above, along with MAC headers are probably the best mid-lenghts out there.

Then whatever y-pipe with hi-flow cats, and then the cat-back you'd like to go with, like Borla, ect.

 

Ok thank you... so FLP will pass emissions, thats good... about the visual inspection.. a guy on the board (can't remember who though) he said that all they did was take a mirror to have a look under the car and since the cats are realitivly in the same position (not the exact but close) that he passed him. I'm not too sure how strick they are up here.. never had to worry about emissions... but I'm sure they can't be too harsh in good ol' Canada

Edit: if thats the case and you pass emissions.. I'd definaly save up and go with FLP

Trevor

 

Hell, with all this talk about emissions, I'm gonna have nightmares. A lot of people have said that my LT4 HC setup won't pass emissions because it's an "offroad" kit only. Hmmmmm. But then on the other hand, I've heard from numerous sources that there will be no problem with an LT4 HC setup passing emissions.

As for headers, I've got the Hooker LTs. Are the HC setup and the LTs going to cause a problem with passing emissions?

I'm also in Maryland.

I've also got a set of the DMS performance springs, in which I am installing this weekend. Are my LTs going to clear with the DMS springs? DMS told me there wouldn't be any clearance problems, but I'd like a second opinion. I don't feel they guys at DMS are feeding me BS and telling me it's chocolate icecream, but they are in the business to make money, regardless of what their ad campaign is. Is anybody here currently running this combo?