Rockauto Budget Y-pipe
 

Hey all. Thought I would share this budget y-pipe I picked up from Rockauto.com. The brand is Davico Manufacturing. It was $38.79 plus shipping which was $14.xx for me. I was skeptical for that price but I needed something in a pinch since my HKS one is falling apart( info to come in another thread). Upon receipt I was pleasantly surprised at the build quality but disappointed in the pipe size. Inlet is 2-1/8" O.D. vs. 2-1/2" for the HKS. Internally the split at the Y looks decent. The pipe to the mufflers is 1-3/4" O.D. vs. 2" on the HKS. Reason I say disappointed was this was listed as a direct replacement part for a turbo car. I may have mistakenly thought their stock pipe sizing was bigger than this. It is thinner walled as well. None the less this would be an ok replacement for a y-pipe on a stock n/a if you're tight on funds. Probably not a performance upgrade. Also the other bad is though the bends are smooth they do decrese the pipe size unlike true mandrel bends. Like I said this in a temporary soloution for me till I get a welder and learn to weld. Then I will order some nice bends and build an exhaust of some type. Here are some pics.

this plus the bosal mufflers and the streetable header from RB on an NA setup is actually quite nice with a bit of welding work. I have it.

I can see this good for someone on a budget with a rotting exhaust system, but I would not count on this setup for performance. I'm also how even your exhaust tips look after, but I guess for the price you really cant complain

Yep, that is my thought as well, and where I was at with sections of my old cat back when I bought it( one of my tips actually fell off). The thing that bothers me the most is the inlet size. Since the outlet of the RB pre-silencer is 2.5" and the inlet of this is 2.125" the transition between the two isn't smooth and I feel the O.D of the pipe is too small before the split. For a stock car though this is an ok budget option. As to the exhaust tips the stock mufflers have a bend shortly after the flange so I Imagine everything would line up and be fine. I put these on I got from Ebay and whoever built them has the bend too big so they are angled funky if looked at under the car. From the rear they look fine though.

https://www.rx7club.com/attachments/...-mufflers1.jpg

I could see how with some welding/fab. work to smooth out the transition into this so it's not an abrupt change like mine currently is it might not be too bad. Plus for the price one won't feel bad about hacking it up.

I wouldn't touch that y-pipe with a 10 foot pole, it looks terrible.

I'd rather spend the money and have one made. I understand being on a budget, trust me, but man that looks bad.

Yeah. I knew going in the bends weren't going to be great 'cause even on rockauto's site I could tell the pipe got smaller at the bends. What I didn't anticipate and is still my only issue was the pipe diameter. Reason being this statement on RB's site " The Racing Beat Y-pipe is slightly larger in diameter than the stock non-turbo Y-pipe, and matches the diameter (2.5" OD) of the stock TURBO II Y-pipe. " Since this was listed for a turbo on rock auto site I rolled the dice. My thinking was since I have been wanting to learn to weld anyway, once I got a welder I would cut out the crappy bends and y and put nice bends in there. I now don't think I'll use any part of this piece because of the pipe size. I mistakenly thought it would have a 2.5" inlet. I guess I came up snake eyes.

My other thinking was I'd be a guinea pig for you guys and get it and post up pictures so if anyone else saw it and thought about getting it they might stumble on my thread. Then they could decide whether it was terrible or usable from better pictures than on rockauto's site.

In the end I'll do as you suggest and make my own.

I am absolutely not the most experienced person on here, but the one thing I learned was to listen to my father when he said that unless it is a high-end aftermarket part 90% of the time you're going to have to modify it a little bit to fit. The first time I ever tried to put up a dual cat back was a aftermarket pipe job with some Midas mufflers, and when I put it up the driver side was scraping the bumper like crazy in the passenger side was hanging about 3 inches too low after that I never again trusted anything but name brands for exhaust parts. All of my RB stuff and Borla I have been absolutely on point

Edit: I am not stating that Borla or RB super high-end, but they are surely repeatable companies

It looks... Okay. But, I wouldn't step down in size in the middle of an exhaust setup. I feel like that's just a problem waiting to happen.

Here is a picture from under the car after mounting and one from the rear though it doesn't really pertain to the Y. Please ignore the dirt and the fact the car needs paint.

How does it accelerate with the downsized Y pipe? Can you notice a difference so far?

My guess is it may pick up a little in low and mid-range, since the narrowing will force higher exhaust velocity and better scavenging as a result, but the reduced capacity and the turbulence from the abrupt transition to narrower pipe are bound to hurt the high end - probably 5000rpm on up. I saw the opposite when I went to a larger, freer-flowing exhaust - a bit less low/mid-range torque, but more power from about 5000 on, and the engine would pull strong to about 8600, where before it ran out of breath at 7800-8000rpm.

That is the same stock replacement unit that came on my car. The PO had taken the car to the Mazda dealership and that is what they had installed along with the same brand mufflers. It was nice and quite with the stock exhaust manifold and cats as well as the Catco replacement cats. I may try it with the CorkSport header and main cat to see if it is any quieter than the over sized Borla pipes and straight through resonators.

Here is somewhat of a companion thread to this one where I give a little more detail on the results. https://www.rx7club.com/2nd-generati...ement-1079600/ Basically I can't really tell much if any difference. Still pulls strong all the way to redline. My thinking is the HKS were a straight thru style but not a true straight thru muffler. See attached picture. Hence now the mufflers have better flow but now I have the abrupt pipe size change and reduced pipe size of the Y-pipe so it all becomes a wash. The restriction of the Y is offset by the increased flow of the mufflers. I am curious to see if I notice any change once I get a proper setup.