Hello all,

New owner and first time poster here.

I recently picked up a super nice stock 1999 FD Type RB-S.
The car is so nice that I don't want to do any serious mods too it at all, certainly nothing that wouldn't be easily reversible anyway.

One thing I would like to do though is give the car a bit more sound, so I have pickup a cheap catback GReddy CS-GTS, Jasma Comfort Sport exhaust from Facebook marketplace.

I have seen many threads that mention exhaust system changes can cause over boost issues. But most of these people are running downpipes and more often than not cat deletes.

What I haven't seen mentioned is if anyone has ever had an issue with just a catback?

Will I be okay to run just a catback exhaust with the rest of the car completely stock?

 

perfectly fine with no issue or threat. just enjoy the sounds

 

Post some pictures of the car! Seems really nice.

 

You should be fine if the stock cat is present. I'm assuming you're in the UK so there might not be a pre-cat as standard in that model.

Do you have a boost gauge installed? If not, definitely get one.

 

It's done just 16,000 miles and is completely original apart from a Mazdaspeed shift ****.
​It has an interesting history, these later cars were never officially sold anywhere outside of Japan but this one was imported as part of a factory order of RX7s by T W White & Sons (Mazda franchised dealers), arriving in the UK in September 1999.

 

Yeah I am in the UK, but this is a JDM spec car so it only has one cat in the middle of the car.
No I don't have a boost gauge, could you recommend one that looks super OEM?

 

Does your car not already have one in the cluster? I feel like it should

 

Oh yeah it does, I just thought maybe it was being suggested because it's better to have a more accurate one?

 

I’m with the others. You’ll be fine from boost creep (overboost) as long as you keep a cat in the system. Even an hi-flow cat which should add just a little performance and easily reversed if so moved.
And I’m a little envious on having a stock boost gauge. But gauge talk made me think of a parameter that imo is even more important to monitor….engine temperature. And unless there were major improvements on your model, it’s not linear, making it as near-worthless as our earlier models. I would strongly consider a decent aftermarket linear gauge. Again, it’s a pretty easy install and easily removed for those concerned about uber-stock.

 

Hey, thanks for the reply regarding the overboost stuff.
I think the boost gauge on my later model replaces the oil temp gauge so I only have water temperature.
Which I'm assuming means I have even less ways of telling the true engine temp as it stands anyway.
Perhaps little digital thing that gives me water and oil temp, how do those gauges work? Do they plug into the ECU somehow or does it need a separate sensor?

 

IMO, on a solely street driven car monitoring both oil pressure AND oil temp is a bit overkill. Not certain but I don’t believe any FD ever had a stock oil temperature gauge. Monitoring engine coolant temp is the priority. The stock gauge will usually sit just below the mid-mark from near normal operating temp. But if it ever moves beyond that, it’s often too late, and there is no alarm. There is a low-level alarm on the stock gauge on my S6, which is probably the only redeeming value.

 

Typically the aftermarket gauges have sensors you have to install into the system. So for oil temp and pressure, you would install a sandwich plate on the oil filter pedestal which has the fittings for these sensors to attach.
Like this one Blitz Oil Pressure and Temperature Sensor Attachment Block - Type-D - RHDJapan

For the Water temp, there is usually a aluminum tube that fits inline with one of your radiator hoses, so you have to cut the hose and install the tube with the temp sensor.
You can see mine in this video around the 10:10 mark.

 

Yeah that is a very conservative exhaust too. MAYBE with a super giant wide open exhaust you could have issues but with the stock cat and stock air box you are well in the safe zone.

I would definitely see your boost before and after to make sure.

Dale

 

So far from my testing, the stock JDM downpipe and the factory cat are the choke point. On the dyno I saw ZERO gains installing a Catback on my JDM FD otherwise bone stock dynoing back to back on the same day and same dyno. Now it wasn't a super high flow canister type like an N1 and the conditions weren't the best (Very Hot) but it was a 3" and I didn't see any gain or raise in boost with the stock vs Apexi catback so I'm willing to bet that you would still see minimal gains if any with a higher flowing muffler since the factory downpipe is so small and the factory cat is a pretty large restriction.

 

Thats cool with me, I am not looking for any power gains, I just want some more noise and no engine issues haha.

 

These things are incredibly fun to drive stock or mildly modified. I'm definitely taking the "old man" approach to my car. Keep it quiet, keep a cat of some sort so it doesn't stink, keep all the creature comforts and enjoy driving the car in hot or cold weather. Keep up with my Youtube channel because I'm essentially documenting all the bolt on mods and the affect they have on these cars until I get to the point of needing a tune, then I'll have to address which route I'm going to go because eventually I do want to do a high flow cat which will create a boost creep situation.

 

FWIW I bought my car with a Bonez DP and Bonez Hi-Flo cat. Over the many years I’ve run a Greddy SP and RB Dial tip with it and never saw creep. From a brief drive of another stock car I think it helped with boost response a little but probably not much more power. Regardless, you can’t really tune for creep anyway.

 

I have heard that an Apexi Power FC ECU and a cat back can take my car from 260hp upto 300-315hp. Is that right? Probably something to consider.
But like I mentioned before, the car is so nice, unmodified and valuable these days that I don't think I want to do anything apart from add a bit of noise to be honest.
Once I have financially recovered from this purchase I think I'll pickup something else that I care much less about and that I can tinker with.

 

It would take a little more than that but with simple bolt ons you can get there. You have the better turbos which will last longer under higher boost which helps. The intake I noticed just a little more response but best of all, the Turbo noises......the number one thing to remember is, make sure everything in the car is in good shape before actually trying to add power. These cars are getting up there in age and you want to make sure the fuel system is in good shape, cooling system, all rubber hoses etc.


That's kind of what I'm hoping with my setup and will confirm on the Dyno. Eventually I'll be going to the HKS super turbo exhaust which is pretty much the same thing I'm running just new and better looking. They don't flow as much as a can type which is fine. I'm interested to see the different the Knightsports downpipe makes with boost pressure and creep. My hunch is that it will increase boost by a pound or so just because of the expansion allowance right out of the turbos. I honestly believe even the JDM downpipe is the main chokepoint in the exhaust even over the factory cat. I'll be able to compare dyno to dyno the boost plot gain from each mod, next dyno is the new intake, then will be the downpipe.

 

With basic bolt on's, you could easily make over 300rwp. But that car seems like almost collector grade so I would just do the cat back.

Feel free to read a lot of the old maintenance threads, but I would highly suggest doing basic maintenance items. Replace Fuel Filter as these are commonly overlooked, spark plugs, oil, differential and tranny fluid.
I would also add Techron Fuel system cleaner(large bottle) with each gas refill. This will hopefully work out any buildup in the fuel system, especially sticky injectors. This will also help potentially knock off any carbon buildup inside the motor.

Congrats on the new purchase.

Eric

 

I'm glad you agree with me on not messing with it. I think that's the right thing to do.

The fuel filter was done about 5 years ago according to the previous owner, I've heard it's a massive pain so I hope I've got another couple of years before I need to do that.

I'm booked into a reputable rotary shop and getting the engine, diff and gearbox oil changed at the same time as I get the cat back on next month.

Spark plugs looked good when I had a compression test done the day before I bought it a couple of months ago.

Fuel system cleaner is probably a good idea that I haven't thought about. Thank you.

 

At 5 years of barely any driving, I would do the fuel filter first, then techron fuel system cleaner.

​​​​​​The fuel filter is a tight squeeze and probably a few bruised knuckles. There are a handful of write ups you can find on how to change them out.

 

I agree with this, especially if you have ethanol in the fuel where you live. In addition, I run a can of B.G. 44K in the tank once a year.

 

Understood, will do.

Thank you.