I have headers with the Y-pipe and a 3" cat. It goes to 2 1/2" the rest of the way. How much if any would my performance benefit if i went to 3" all the way back? With my mods i figure im running maybe 300-350 hp. I also have an electric 3" cutout i want to install but is it worth it with my current setup? Wondering if i should spend that money on other mods and do the exhaust later.

 

Yes! I don't know why you haven't done it yet. It will allow your exhaust to flow better. Kind of like drinking a bottle of exlax when you're constipated

 

I have a 3" Exhaust with a cutout that dumps before the cat. I can't really say too much more than that though, as I bought the car with the exhaust already on it.

But what I can say, is it sounds really nice.

 

I imagine you won't actually see any gains performance wise replacing your 2 1/2 with 3'' on a stock car, but since you're running 6.5 psi boost you might see a decent gain going to 3'' w/ a cutout. To me just cuz of the boost would warrant the 3'' w/ a cutout. The flowmaster is definetely holding you back a little.

 

The 2.5 inch is definitely a restriction and probably costing you a little power. You can either go with the 3" catback which will run you some money, or get the same results with the cutout and keep your stock exhaust.

 

i gota 3.8 with stock headers after the to pipes meet in the y pipe? its starts at 3" them running to a 3"il an 3" ol new cat then 3" back to the rear end with a cut out then 3" the rest of the way to the magna flow exhaust

 

The muffler shop said they could get the 3" pipe to run after the cat to the muffler for $120 and install it for free. So if i put the cutout in and left the rest the same it would be 3" all the way to the cutout. That sounds like the cheapest way with getting the most power when i race.

 

Or just have the cutout put in right after the cat and leave everything else alone.

 

Do you need to keep the cat?

 

Cat needs to stay.

 

I wouldn't worry about it too much, a high flow cat is going to do very little, if any, damage to your numbers.

 

Off topic:

But how is your 6.5 Powerdyne unit Mr.Mint? Is it worth buying? I found a place that sells them right under 3 grand, my knowledge of centrifugal's only consist of Vortech's, but I was just wondering how they stacked up?

Huh?

 

I would go another route if i did it again. The quality is a little low and the instructions were the worst i have ever seen. I was not making the power i should have been making so its been 1 1/2 years of slowly gettting the performance i think it should have had the first day. I would have sold the car already if it wasn't for this site. Buying a used one for under $1000 might be the only way it would be even close to worth it. I learned more about our car than i wanted but it feels good to have done it all myself.

 

Are you saying you have a 2.5" intermediate pipe, from a single cat to a single Flowmaster muffler? That would be smaller than the stock intermediate pipe. And you are saying your LT1 engine, with 6.5 PSI of boost is only making "300-350HP"?

 

Dang, sounds like something is wrong man. My buddy here in town runs a powerdyne too (just found out) on his 97 T/A. He showed me a dyno chart from a shop in Montana where his car was putting out 388/377, and all he has is LT's, hooker exhaust, and a dyno tune. Has your car ever been dyno'd? It sounds like your exhaust will waken up a lot if you go to 3'' all the way. With the boost on your car, I wouldn't be surprised if you gain 20-30 true hp with headers and a cutout.

One thing is for sure, that flowmaster need's to go. Your stock muffler is probably better. Something just doesn't add up, are you sure you might not have a blown ball bearing in your centrifugal? I did a little research about Powerdynes and it turns out that if you have a sound like someone blowing into the opening of a bottle, you might have a defective sc'er. Powerdyne give's 3 year warranties on there systems to, so maybe you could get a new one.

this guy had that problem : http://www.eskimo.com/~cjessup/ckjz28sc.htm