Ok, so I'm wondering if I should go with the Cattman headers, or a 3" Y-Pipe (made for SC'd cars)

From what I've been able to gather, the 2.5" Cali Y-pipe showed a big increase over stock and the Fed spec Y showed a very small improvement over the Cali one - is it even worth it?

I haven't seen any numbers (that I can find) regarding C-man's header installed on a 2K yet, just the drop in numbers on Steallins

So I guess I wanna hear what you all think is best/worth it: A 3" Cali spec Y-pipe or C-man's header setup?

Should I go with the header just because it gets rid of the single pre-cat left, even though the numbers for cali vs. fed Y-pipes don't show that great of an improvement? - At least from the one page that I found this info on, maybe there's a bigger difference than I think?

I'm thinking that if the 2.5" Y-pipe gains, let's say, 15-18 hp and the headers gain 18-20 hp, then an extra $450 for the headers is a lot for an extra 3-5 horses...

 

1)Cali over Cali->Fed conversion made minimal difference. BOTH y-pipes give 10-13whp IIRC.

2)I'd ONLY go 3" IF you can afford to go 3" all the way to the muffler tip. It's not cheap and it requires custom work for the rear section/b-pipe. Last, it's going to be FUKING LOUD!!! Never heard a 3+" setup that's quite.

3)How much boost are you planning on running? I think most here are running 2.5" exhaust and Kev was laying down ~300whp with 2.5".

 

so how much boost you plan to run? the only person with 3" system and SC on .org is mardigras max and he was running 14psi with juice...plus lots of tools to monitor and cool his engine. I would save the 3" Y pipe money for something else. (have you looked into gauges???)

if you dont plan to run high boost....3" exhaust system is not going to provide any gain. If you plan to run high boost....look into intercooler and water injection first before you blew something.

if you really want a 3" y....you will have to spend more on a new 3" cat-back.

save the money on monitoring/tuning devices.

 

I've been trying to figure out the amount of boost... I actually asked if anyone knew if there was a calculation to convert impeller speed to boost psi... no answers...

I'm going to take off the UDP and put the stock crank pulley back on, then run with a 3.17" blower pulley - the vortech calc says impeller speed @ 6400RPM would be 45425.87... any idea what this boost is?

My buddy says the rule of thumb is about 2lbs for every 10K impeller speed, so that works out to just a hair over 9lbs - at redline...

the steallin Y is 2.5 inches right? or is it 2.25"?

 

3.125 should give you 11psi of boost. check out the 5th gen FAQ for other pulley's spec. but the amount of boost received at throttle body may be varied...it depends on your BOV tighteness, type of BOV, etc.

the calculation was there to show the impeller speed decreases when the crank pulley size becomes smaller...it doesnt calculate amount of boost. About 2psi per every 10k of impeller rpm....I dont think it applies to vortech centrifugal SC, I plug in 2.62 to that calculation and get 55k at 6400rpm. Mardigras used to have 2.62 and he got 14psi on his gauge.


stillen y is 2.5"