HiTech5

iTrader: (4)

Camaro_Nut - Using 1 3/4" headers on your mild small block is overkill and you WILL lose low and midrange power. For your application a 1 5/8" header is more than sufficient.

I have seen larger and healthier motors than your run very well on 1 5/8 tubes.

www.geocities.com/dzperf

CrazyHawaiian

Well sorry for asking questions, but thanks for answering them. I'm gonna be giving Mufflex a call.

Marc 85Z28

iTrader: (3)

Ummm... NO. Again, like the 3" to 4" catback swap, I GAINED power when I switched from Edelbrocks 1 5/8" shorties to SLPs 1 3/4" shorties. You might have the shorty (which nearly ALL shorties for our cars are technically intermediate length) and long tubes mixed up.

As far as the 3.5" or 4" Camaro_nut, its up to you. 3.5" will support up to 400HP just fine. A 4" system will support more future mods - which you will eventually do BTW Not only that but IMO the 4" sounds much deeper.

As far as my ground clearance: Its the same as with the Hooker 3" I used to have. I slightly modified my Mufflex 4" catback to fit my car as it was an original LS1 catback. It took me a couple of hours of trial fitting the over the axle joint to get the angle just right for clearance issues. 4" is pretty large, and it fits, but it WILL require some patience to get it clear everything with good ground clearance. The 4" tucks up very nice, and everyone assumes its a 3". I've had it scrape once on a dip, but that was with 2 passengers running over a dip in the road at triple digit speeds Speed bumps clear fine. I have more issues with the air dam than the exhaust LOL!

One more thing to note, I believe I stated this previously but the Spintech is what I would call a more street oriented muffler for the Mufflex. I originally had the Spintech with the 4" inlet and dual 3" out. Sounded nice, smooth too, but way too tame. Sounded too much like a late model truck. I traded it for the single 4" in/out Flowmaster and WHOA! That's the sound I was looking for. Its quite loud, interior resonance isnt too bad, but worse than the Spintech. But at WOT its definately worth it. The Mufflex 4" with the single in/out Flowmaster is VERY loud!

Man I sure wish I had a way of converting VHS to digital video. I've got some killer vids!

HiTech5

iTrader: (4)

Marc 85z28 - "Ummm... NO. Again, like the 3" to 4" catback swap, I GAINED power when I switched from Edelbrocks 1 5/8" shorties to SLPs 1 3/4" shorties. You might have the shorty (which nearly ALL shorties for our cars are technically intermediate length) and long tubes mixed up."

To clarify, Edelbrock headers are a combination of 1 1/2" and
1 5/8" tubes. I do know the diff between shorties and long tubes.
I have had 4 different sets of headers on my car over the years. I speak from experience!

FWIW - I am running Hooker Super Comps and Mufflex 4" on my 406. I still strongly believe that it's overkill on a mild 350.

www.geocities.com/dzperf

Fastbird

iTrader: (5)

I have to agree here. Running Hooker Super Comps with a Mufflex 4" system on anything less than a 383 is overkill and could hurt performance.

aaron7

iTrader: (7)

I have 4" exhaust... on my turbo minivan (long story).

I run 3" on the Iroc. I didn't notice any difference from the 2.5, so I don't think I'd notice a change (a better one that is) with 4".

The guy at the local parts store has a turbo diesel pickup with 5"!

Marc 85Z28

iTrader: (3)

The OLD Edelbrock TES had the dual diameter primaries. The newer ones, which came out just a few years ago, have all 1 5/8" primaries.

Overkill for a mild 350 maybe. Depends on your definition of mild. Some call a 300HP, 5500RPM 350ci engine mild, while others have claimed 450HP, 6500RPM 35ci engines to be mild. Regardless, if you're moving enough air to produce over 425-450HP, you're setup is the way to go. Several people on this board have documented gains from the shorty and 3" system to the LT and 4" system.

But like I've said so many times before, I saw power gains from both the larger diameter primaries and the larger catback. That's my experience (on a mild 350 ), and yours may be different.

Nice car BTW! I still can't get over how funny it is seeing your "LT1" intake with the rear mount distributor...

25THRSS

How do you know you gained anything? If you didn't dyno it before and after it's all a guess and means nothing. I've got a 3.5 inch on my 550 hp engine and it's plenty.

AD9CHEV

I'm no expert on exhaust systems, but I've spent much time with people that are. We used to run Porsches, both turbo and NA, and exhaust can surprinsingly affect more than you thought. As the exhaust travels away from the head, it cools. I've seen as much as several hundred degrees in 2 feet. When it cools, the velocity of the exhaust slows down, causing a pressure build (the old math thing, when velocity decreases, pressure increases). In order to accomodate the pressure increase, area (tubing) must be increased (enlarged) to maintain flow. Ideally, a gradual increase in tubing size is called for, but something in that length isn't made. Same applies for turbo cars (I saw above someone was going to add one). We've ran 500 RWHP through 3" of pipe from a 2.5L I4 944 Turbo engine. 4" made absolutely no difference. It goes back to the increasing area accordingly as the velocity of the gas slows. Just make your downpipe run just before the muffler (if used), and put the muffler as close to the engine as possible. Also on the turbo, your downpipe should match the diameter of the turbine outlet or you can cause turbulence that would further restrict the exhaust flow. My .02

Marc 85Z28

iTrader: (3)

1. I can feel power increases/decreases pretty well in my car. I drive it almost everyday, and have done so for 8 years. I can notice even the slightest changes in my car.

2. I can measure my performance before and after mods against several friends who I race fairly often.

3. Because when my Snap-On scanner tells me that I'm I can go from 70-100 in third gear faster than before a certain mod, I tend to believe it...

1 + 2 + 3 = no need for a dyno.

And about the 3.5" on your 550HP engine. How do you know its "plenty". Have you tested a 4" on it?

AD9CHEV

Not trying to be a dick, but ambient air temp, air pressure, humidity, elevation, incline/decline of the road, oil temp and viscosity (effort crank uses to spin through it)...all of these and more can affect what goes on with your car. Any good dyno has these conditions controlled for exact same readings every time you go in there. Try to avoid the out door dynos at car shows and such.

KagA152

iTrader: (5)

my buddy runs hooker long tubes and a 4 in mufflex system with a flowmaster on his juiced 355 and he traps at 145

Marc 85Z28

iTrader: (3)

I understand that. But my point is that I drive it through all sorts of conditions, at all times of the year. When comparing 2 separate events, each with different mods, those factors become important. However when comparing several months, through all sorts of conditions, a trend starts to appear.