I just purchased the FULL Ceramic Catted Street Header package that I will be installing to replace a FULL MAX Header package. In other words, I'll be replacing all parts (headers, HH mid-pipe, and SQ muffler). That may sound a little crazy, but ....
The main reason I'm doing this is because I currently have two NC Miatas (2007 and 2009). My setup is as follows:
2007 Touring, Bing Cherry, GWR Ceramic Street, HH Mid, SQ, ME CAI and Tune 2009 Sport, Silver, ME 2.5L 1.5 Cams, GWR Max, HH Mid, SQ, ME CAI and Tune, Happy Meal, AWR 1D Roll, Koyo, Ohlins, RX8 Sways
I want to replace one of them with an ND2 in the near future. So the obvious choice (in my mind) is to let go of the 2.0L and keep the 2.5L beast. But I need to tame it down a bit, for the commute. The mid-pipe on the 2009 recently developed a serious "crack" around the cat that a trusted mechanic has determined is not reparable. Thus, a full front-to-back overhaul of the exhaust with shiny new bits makes sense to me.
Anyway, my question is: How does the header install differ when swapping out a MAX header with the Street header? Will the install be any easier? Also, will the 2.5L engine necessitate any different treatment?
NOTE: I did not originally install the exhaust on either of these cars, but I'd like to give it a whirl this time around. I do enjoy wrenching just for enjoyment, though money is not a deciding factor for me. I have more experience working on my sport-touring motorcycles (BMW K1600GT and FJR1300ES), but I'm not a complete novice working on the Miatas. I've done a variety of smaller upgrades myself.
Re: Header Installation
Posted: Sun May 19, 2019 8:13 am
by Brian
The catted headers and catless headers bolt up the same way, the only difference is what happens with the O2 sensors per the prior pages here. Fortunately 2.5 or 2.0 liter makes no difference.
Re: Header Installation
Posted: Mon May 20, 2019 2:58 am
by BennettS484
Thanks Brian.
Re: Header Installation
Posted: Mon Oct 28, 2019 8:02 pm
by Brian
Thoughtful ND Header install video by Customer Ron Cook
Re: Header Installation
Posted: Sat Mar 21, 2020 11:21 am
by MichaelC991
Instead of buying the header to midpipe flange studs from Mazda these are a very nice alternative that is much cheaper. Dorman #03123 exhaust bolts set. It says it's for Toyota but it works perfectly. M10 x 1.25 bolts. They were only $12 in stock at my local parts store and they are also on rockauto for even cheaper if you search the part number on their site.
MichaelC991 wrote:Instead of buying the header to midpipe flange studs from Mazda these are a very nice alternative that is much cheaper. Dorman #03123 exhaust bolts set. It says it's for Toyota but it works perfectly. M10 x 1.25 bolts. They were only $12 in stock at my local parts store and they are also on rockauto for even cheaper if you search the part number on their site.
So I’m curious about the helmholtz midpipe, you offer a 4 or 5 inch. I’m going to be doing a 2.5 swap soon but I have an automatic so I have to use the 4 inch midpipe, what are the draw backs of not using the 5 inch midpipe on the bigger engine?
Re: Header Installation
Posted: Tue Apr 28, 2020 5:16 am
by Brian
DonovanS079 wrote:So I’m curious about the helmholtz midpipe, you offer a 4 or 5 inch. I’m going to be doing a 2.5 swap soon but I have an automatic so I have to use the 4 inch midpipe, what are the draw backs of not using the 5 inch midpipe on the bigger engine?
The 5 inch will flow a bit better at high rpms and power levels beyond 250hp, more relevant to turbo customers, you won't find any difference on automatic and normally aspirated 2.5.
Re: Header Installation
Posted: Sun May 24, 2020 6:48 am
by KevinB238
Hi Brian. I did the 1.8 header and midpipe this weekend on my NC. When moving the studs from the downstream connection on the old header to the new header, I noticed that the side of the studs that goes into the header flange is not long enough to screw a nut on it. The stud is threaded into the header flange and then the spring is compressed on the midpipe flange, and that’s the only nut holding that connection in place. Is that correct? Or do I need to buy new studs so I can put a nut on the header side too?