I am going to do a Hooker long tube and mufflex y-pipe install on my Z this weekend. I ordered new 3" piping from dynomax as my exhaust is really tore up and cobbled together. On to my question...

I just got the 4" to 3" reducer to mate my mufflex y-pipe to my cat-back which will be 3" with a Dynomax ultra-flow muffler. When I put the reducer on the y-pipe, the 3" looked awfully small. What I am wondering is will this 3" exhaust be very restrictive? Will it hurt power? Would it be worth it in your opinion to move up to a 3.5" or even 4" exhaust? How big of a increase was your Hooker long tube/mufflex y-pipe 3" exhaust over a shorty header and 3" exhaust? My mods are in the sig.

Any info or insight would be helpful.

Thanks,
Jeff

 

I dont think a 3" catback would be restrictive on your car with your mods. The y pipe is only 4" for a couple inches so going back to 3" for the catback wont be a problem. If anything the muffler will soak up more power than the diameter of the tubing will.

Some who go to 4" say its too big unless you have drastic mods...like a stroker, etc.

Oh and with my GTP head cam old set up I gained 40 rwhp with LT's and a dynotune over SLP shorties and an Ed Wright mail order tune.

 

Anyone else want to post thier gains with the Hooker long tube and mufflex y-pipe with a 3" cat-back?

Jeff

 

30+rwhp with my current mods, I have the SLP SS 3 inch cat back system w/ the twin 2.5 outlets on the driver side...sounds really nice.

3 inch exhaust is pretty darn big, 4 inch diameter pipes aren't really necessary unless you have really radical modifications. Although bigger is better...

 

Here's some realworld data for you:

I went from a 4" mufflex exhaust (Hooker LTs, mufflex y-pipe) to a stock GM WS6 (2.75) + cutout. The only major thing I lost was a TON of exhaust noise. I do lose about .3 of a mph going to the cutout from the stock GM exhaust. (This is a bolton car)

However, it looks pretty pathetic going from dual 3" > single 4" > single 2 3/4".

From my experience different catback systems are not THAT big of factor. Sure, the more power you're making the more it will hurt you, but 1-2mph for a car under 120mph its not enough to sacrifice (on a daily driver) having a loud exhaust that mandates earplugs. IOW: mufflex 4". Even on my weenie bolton car a WOT blast was just shy of sounding like an open cutout.

I've had 4-5 exhaust setups and finally content with my current setup: GM WS6 exhaust modified with hidden dumps. Quiet, looks good (because its not there), sounds ok, and flows enough to make a little power.

HTH,
Ryan

 

Cool, thanks for the replies. It seems that I will be not loosing any power. When I put the reducer to the y-pipe the 3" looked small and I thought that it would be a restriction to the flow of exhaust.

Where those gains over shortie headers? Also is there any good install guides on the web? I did a search and couldnt find a good one.

Thanks again,
Jeff

 

About the only problem you will have installing is probably the driver side of the Y, atleast I did, I had to grind a little off the crossmember with an air grinder to get atleast more than a 1/2 inch clearance, and you will be getting rid of that stamped flat piece of metal that goes across the drive shaft if you haven't got rid of that already, it will not fit and will be right on the mufflex's 4 inch collector.
I could go on and on, but it came down to me cutting off the driver side of the Y-pipe and welding on a custom 3inch mandrel piece that I made myself for clearance issues.
and I highly recommend those exhaust wraps, man those worked wonders for me!! no exhaust leaks...