ok today I pulled the stock DP off and got the new one up, the only problem is the 2 foot wide stock cat is hitting the car when I attach it to the DP. The new DP hugs the bottom of the car a little more than the stock one.


I am running a stock intake, and stock exhaust with no other mods. Will I be ok with getting a highflow cat with the back pressure considering I still have the stock muffler? OR with the stock muffler is there enough back pressure to run the test pipe?


Also where can I get a highflow cat with the correct lengths welded? That isn't going to cost me an arm and a leg..

 

Some DP's don't fit with the stock main cat. You might have to run a hi flow for the two to fit. As far as the "test pipe", I'm assuming you mean a midpipe. Is doesn't matter what cat-back you're running, you always run the risk of creep with a MP and an unmodified wastegate.

 

I would consider a different downpipe if your having fitment issues. Most downpipes shouldn't cause any problems.

But a highflow cat is not too expensive either. You can grab one from rx7store.net or just about any other online rx-7 vendor. You should still have enough back pressure to prevent any type of boost creep. A midpipe is another story.

Plus the main cat is no light weight piece, a dp and high flow cat is a decent weight reduction as well.

 

I have a hi-flow cat with less than 10k miles on it. It's a Bonez hi-flow cat. PM me if you're interested.

 

The cheap Ebay downpipes and midpipes have hit-and-miss fitment problems. Some of them were only designed to be run with the midpipe for an OK fit.

I have a cheap Ebay midpipe that I bought for testing, and it pulled the back of my exhaust system up, making the exhaust bump the car under certain occasions.

If you get a high-flow cat, it likely won't fit well either. You need to get a decent downpipe. Good downpipes are a dime a dozen used.

Dale

 

joeydinc,

Just take the car to an exhaust shop. They'll get everything to fit for you for a lot less then you are going to pay for a high-flo cat.

 

^^

Dale's words are what you should listen too. I would recommend that you go for a quality DP in the used parts section, one with a reputed fit ala HKS. Also, a quality highflowcat Rx7Store, Bonez etc. This is because later on if you ever decide to go with an aftermarket cat-back you won't have to worry about switching out your midpipe for a highflow cat to control restriction and don't get that boost creep...

Alex

 

^^This is my experience also. My Bonez cat was bumping the trannel tunnel b/c of the downpipe.

Its kinda hard buying a used DP b/ they've changed hands so many times that you can't be sure who made it and what fitment issues you may have.

Buying a cat used you have to consider why its being sold and how much life there might be left on it.

One last thing fwiw, my DP is "name brand" from one of the online vendors, not an ebay DP.

 

I think I'm going to keep this DP, I talked to a friend who said the same thing as gracer7 about his name brand DP, and if it's not to bad of a price I'll just buy the Highflow and keep the stock exhaust for now.

 

yeah, what kind of downpipe is it? should stick with good name brand stuff. The HKS is great and only costs like $200 bucks.

 

well it's an Ebay special, but honestly, you can't really tell me there's much difference between the ebay DP and one that costs twice as much. OTHER parts of the car, ie thermostat, or exhaust, or hiflow cat etc. yes...

I mean yes there's an issue with the main cat working with it, but really I could cheat and just cut away part of the HUGE heat shield that's there, or even beat it in. But I figure I should just do the hiflow

 

Sounds like you got a badly made pipe. I suggest you do as Mahjik says, and take it to a muffler shop so it fits right.

 

looking into it, it seems a lot cheaper to see if I can get somebody to weld on up. because it's over $300 for a ready make one and a $3" universal is about $100-150 and to weld it should be about $75 or so, maybe a little more.


Adam - you been driving your FD a lot lately? I've seen you two or three times now. Everytime I've been in the Geeksquad bug and you go flying past me. HAHA

 

Actually, you need a midpipe first and then a useable hi-flo cat. Those together will run you over $200 and still it would have to be welded.

An exhaust shop will probably charge you $30 to fix what you currently have.

 

I'll have to look for you in the Geekmobile. Usually when I see a bug, I just squash it

Saw your car at Trader Joes about a week ago. Didn't see you.