Hey I was wondering if having a 3" or 2.5" downpipe with stock cat-back would create back pressure since it's forcing higher flow through a narrower pipe?


ReD RaiN

Forgot to mention I have a fat pipe. 2.5" inlet, 4.5" outlet if that makes a difference


ReD RaiN

Could create back pressure.... are you turbo yet? What is the reason for upgrading exhaust? Just to let the engine breathe?

For more POWA Jason lol.... UPgrade the downpipe now and exhaust later I suppose. When I went from 2.25 to 2.5 inch all the way back from the header to muffler (no cat), I gained 8 WHP on my mods. No turbo here yet.


"FRIENDS DON'T LET FRIENDS DRIVE STOCK"

Your profile does not say anything about your exhaust setup. Are we to assume you have the stock exhaust manifold since you say you are pairing it to the stock cat-back? What the hell are you talking about a fat pipe? If at any point in your exhaust (other than your collector) you have a dramatic shift in diameter (like your said 2.5-4.5) you are dumping exhaust gas velocity which is bad. Even if it reduces back down to 2.5 after, you now create turbulence at that section of line which restricts exhaust flow.

No turbo yet, I have a pacesetter header with a 3" outlet, I want a 3-2.5" reducer, then 2.5" exhaust to cat, then stock cat-back (for now) with a race muffler that has a 4.5" tip. Need to replace my flex pipe so swapping the stock header out and then as described. Just was wondering if having a narrower cat-back would create back pressure


ReD RaiN

No need for that flex pipe, delete it. Any time you reduce, you create pressure. If I remember correctly, the down pipe that comes with the PaceSetter is 2.5" which reduces to fit the stock 1 7/8. So depending on how you had it installed you should be at one of those unless you have a custom made down pipe. Back pressure isn't as much of an enemy as it sounds. The lower the back pressure, the lower the exhaust gas velocity (put super, ultra simplistically) which means the motor is doing all the work itself to remove the exhaust gas from the motor.

Yea see the issue is I got my header from a buddy cept I don't have the downpipe. The pacesetter outlet is 3" but I just gonna do 2.5" all the way back. Just peicing things together till I can afford everything. Right now I'm looking at around 400 to install just the header, downpipe, wideband o2, highflow cat, reducer etc. Cat-back is going to have to wait.


ReD RaiN

One thing I learned is DO IT right or don't do it at all. You'll have problems down the road especially once you stiffen up the tranny & engine mounts and other suspension parts. Your exhaust will flex and cause issues. My last set up I dropped 500 for exhaust, straight pipe and magnaflow muffler. Another $225 to install just the exhaust! Best shop in town. Additional hangers, welds etc. I've seen weld jobs from other exhaust shops, no way I'm having that mess done. This place welded like it was done by machine! Got to a good shop man.


"FRIENDS DON'T LET FRIENDS DRIVE STOCK"

I found a cheap header with downpipe from ebay. I know not all piping is the same quality but really how much diff then say a stock custom pipe from a garage.? I was thinking use my pacesetter header with ebay downpipe. Would save me buying reducers, pipes, clamps bungs etc. Plus labor.. Would install a magnaflow cat tho. Jus thinkin that setup is done, mandrel bent etc for a fraction of the price. No shops around here has mandrel bending anyways so can't be much diff as long as it's say t304 quality.. Thoughts?


ReD RaiN

I had mistakened, the flange on the outlet is 3" and reduces down to 2" I believe, with that said I was wondering if it would be smart to try and widen the hole to 2.5"? Keep in mind it's a ball and socket collector. Not sure if I'd have sealing issues... Another note, that ebay deal I seen is for stock direct replacement. Looks like I'm going to have to get a custom pipe made that's not mandrel bent either way needs to be done. Thanks for the help


ReD RaiN

I believe the Pacesetter header for a 99 cavy has a 2.25" collector diameter.

I have had fitment issues for my 2002 cavy when I have bought SS mandrel bent tubing...I think 95 - 99 cavy's have less issues when it comes to that but 95 - 02 cavy's are identical or even 95 - 05. Anyway, you have choices of aluminium or SS. Of course the aluminium is cheaper, but not as durable as the latter.

Check out: http://www.mandrelexhaustsystems.com/

Order any kind of custom tube you need! I bought my SS exhaust system, straight pipe (no cat) and Magnaflow muffler from here.




"FRIENDS DON'T LET FRIENDS DRIVE STOCK"

Thanks I had actually looked into the downpipe with cat from there already but they told me it wouldn't bolt up to the ball and socket style plus it's fitted for a stock header and they wouldn't make a custom one unless u were talking bout buying individual pieces from there. That I never thought about. Will have to look into that. Tomorrow going to pull exhaust so I can get a better idea how much or what I'll need.


ReD RaiN

Well... Exhaust is off. Didn't go to well. Looks like I'm just going to have to replace the whole thing from front to back, sensors etc.. Not going to be a cheap fix. Looks like the cavi gonna sit for a while.. Again.


ReD RaiN

I guess the pacesetter header reducer is 2.25" After all so my next question is, would it be pointless to go 2.5" piping all the way bk since its restricted to 2.25" at the header?


ReD RaiN

I bought a eBay header for 100 and was solid quality only slight mods needed. I got the mandrel exhaust 2.5 from linked web site in previous post and it fit perfectly. You can have a custom down pipe made or I just used the 2.25 which was actually 2.35 so wasn't to much of a deference and welded all up. Haven't put on the mufflersyet put cheapest route to go. By the way it's on a 97 z24 and was duel back exhaust.

Yea I was thinking bout doing the cat-back from mandrel exhaust systems but I'm thinking shipping might be a lil pricey here to Canada. I also considered just buying another cheap ebay header with downpipe included and use that. Got some time to decide while I save some cash.


ReD RaiN

Get a shipping quote. Might not be as bad as you think! Ask for a discount, something!

Don't ever buy anything too cheap, especially stuff like this. You will have more problems down the road. Wait to spend a little bit more for quality. I ended up breaking down and buying a TSUDO 4-2-1 header.. Since 2011 to know, It has seen maybe 600 miles. I got different bolts, copper gasket and tried to make sure I did everything else right to make it last. So far so good.


"FRIENDS DON'T LET FRIENDS DRIVE STOCK"

Thanks for all the responses, unfortunately this is going to be put on hold but I have been in contact with mandrel exhaust systems on doing a custom order with their cat-back. Looking forward to the new powa:p and sound


ReD RaiN

Tsudo will be my next header but I bought a eBay header for my 2.2 cav wrapped with header wrap and was running lots of nitrous. Header would glow red after a race killed engine but header was still in good shape. Had about 30000 miles on header, so there not bad quality but not as good as tsudo.

LOL. Always looking for more POWA Sweet man. They offer some nice mufflers.

Tsudo isn't as bad as I thought - Its a decent quality header (my old RKSPORT ceramic 4-2-1) lasted a long time. Good you saved the header, but I would say Yes, try Tsudo!


"FRIENDS DON'T LET FRIENDS DRIVE STOCK"