Hello,

I own a stock LHD 93 RX7 with a PowerFC. I am planning to start at slow pace some reliability mods.

I am looking between two downpipes at quite different prices and would appreciate some feedback.

1) Revolution Front Pipe 90mm (I can get for around $400)
https://www.rhdjapan.com/revolution-...90mm-fd3s.html
SPECIFICATIONS:
Piping Diameter (mm): 90
Material: SUS304 Stainless Steel
Weight (kg):
-Stock OEM: 7.5
-Revolution: 4

2) Custom 75mm Downpipe that looks like an HKS ($150)
https://i.ebayimg.com/images/g/7aUAA...1W/s-l1600.jpg
https://i.ebayimg.com/images/g/hisAA...1W/s-l1600.jpg
https://i.ebayimg.com/images/g/6eAAA...1W/s-l1600.jpg

New vs Used
$400 vs $150
Stainless vs Mild Steel
90mm vs 75mm

I am also wondering if the 90mm would be plug and play like the 75mm or would have to change the rest of the pipes and about the extra flow, requiring a possible ECU tune.
Also, my car only does, if, 2000 miles a year (I live abroad), how would you guys rate the 75mm pipe in terms of oxidation?

TIA & Regards

 

IMO the 90mm downpipe is a waste unless you're trying to get every ounce of power out of the factory or upgraded twins. I would definitely recommend a quality manufacturer and just go with 75mm or 80mm. RHD Japan has the Greddy/Trust 80mm as well as the HKS 75mm, either of those would be fine and just over $200 + shipping vs that one that "looks" like an HKS at $150.

 

Thank you @AE_Racer . I am not based in the US so the prices for an HKS would add around 100$ more on top of that custom. As I do only 2000 miles a year, I think I will settle with the $150 one, will also help with the annual car inspection as I am replacing old for old rather than shiny new. Anything that is not like the stock pre-cat should already do wonders.
I am not intending to wrap the downpipe (read multiple threads) so I might also buy an used heat shield guard just for some extra layer of heat
https://www.ebay.co.uk/itm/MAZDA-RX7...wAAOSwlvNco0jb

 

My vote would be for the genuine HKS as well. The welds look pretty sketchy on that ebay mystery pipe. You can't have a lot of confidence in the flanges either. Yeah, looking like that it won't draw attention during inspection. But if you're going to the trouble to change it, I wouldn't want to do it a second time because of leaks or failures. Gaskets are kind of pricey too.

 

Sorry the bump,

Another offer on the horizon, Custom and Stainless, opinion on the Sensor location?
https://i.ebayimg.com/images/g/kzUAA...-F/s-l1600.jpg
https://i.ebayimg.com/images/g/L6AAA...-a/s-l1600.jpg
https://i.ebayimg.com/images/g/chcAA...-6/s-l1600.jpg
https://i.ebayimg.com/images/g/X6QAA...-8/s-l1600.jpg
https://i.ebayimg.com/images/g/Ok8AA...~J/s-l1600.jpg

 

It's looks like another Ebay mystery pipe, probably made in China, and probably not from the finest materials. It was probably sold originally with a matching mid-pipe. We'll never know the numbers, but those DP/MP "kits" were probably responsible for several blown engines on these cars over the years from Boost Creep.There is also no mounting ear or provision at the down-stream end of that DP for securing it to the transmission like OEM. That will lead to vibration and potential for gasket failure. But they ARE shiny.

Know that a rotary's exhaust is almost twice as hot and energetic than the average piston engine. I strongly recommend sticking with known and proven brands...like that HKS mentioned above.

 

Convinced! Will wait for the HKS be back in stock