i have a 93 rx-7 with a HKS cat-back and a blitz intank. I wanted to put a down pipe in but am not sure if i need a ecu...i don't know if my car will run lean.I have a air/fuel gauge but i hear that you can't go by that...and whats the best down pipe out there?



thanks Mark T.

I cant answer that, but if you want a Downpipe, I have a Pettit racing one that has NEVER been put on a car that I might be willing to sell.... Just email me if you are interested at: ben97gtp@hotmail.com



If the price is reasonable it is definitely urs since I need to clean the garage out of FD parts

Car will run lean. Remember, 2 mod rule. You need some sort or ecu to richen to fuel mixture.

3 mod rule



mike

car will run leaner but not to the point of detriment..

add the dp....

if your concerned..check your plugs every oil change..

theyll give you a good indication..

dont skimp on octane either...

You can run the intake and catback with a dp.

I did for 6 months even with a PFS Intercooler. You may get some boost spikes but

I dont think you will get so lean that you will pop you seals.



Umm I would take it into consideration that most guys would not recommend that you do it.

You could get a a/f ratio guage to keep an eye on it.

But I am sure you could get away with it until you can affrod an ECU upgrade to dump spme more fuel in there.





Go to Ebay and buy one of those nightsport ecu chips I see on there all the time.

They are only like $30 and it should adjust the fuel and advance the timing for you some.

All you need is a soldering gun to install the chip.

That could hold you over for a while.

Thanks for the post guys

Mark T

if you carefully control your boost, the 3 mod rule will seem like a myth. i still run a hard 10psi w/o and ecu upgrade. althought it seems easy, it did come at the cost of a blown engine once. BUT, with a bigger fuel pump, i have menaged almost 14K miles on my rebuild so far. i have my boost set at 10, and have had no problems. however, i would not recommend this to someone who is power hungry or does NOT KNOW THEIR CAR WELL.....



i have a new down pipe in the back of my car that i am still trying to sell. i got two of them, and my buddy crapped out on me.....150!!! pm me if you are interested...





louis

i used to run my car with a downpipe, midpipe, cat back, intakes, bov, fmic, 255 fuel pump, 10mm wires, and a manual boost controller... on a stock ecu https://www.nopistons.com/forums/pub...#>/biggrin.png but i couldnt go more than 6psi, with boost creep to 8-10psi.... i did go through a motor on that set up tho.. after about a year of daily driving.. about 27k miles when i got my motor rebuilt i put in a HKS F-Con and fcd and everything was fine up to 14psi. but yeah.. this time around.. im gonna follow the 3 mod rule i guess.. and drop an ecu in there when i get an intake...