Hi guys,

I'm planning on getting a test pipe made, along with the HKS Legamax Catback. What kind of HP gain will a test pipe do for the 8?

 

Why not just buy one? I've got the B&B test pipe and muffler. Loud as heck, but supposedly makes like 12whp.

 

Limp, the max HP gain would be ~10hp with a full race exhaust system = Headers, Mid-Pipe, Hi Flow Exhaust.

http://www.racingbeat.com/FRmazda4.htm

From Racing Beat:
The following table lists the measured power gains from various aftermarket components. Testing has been conducted on the Racing Beat engine dyno with both pre-production and production Renesis engines.

1. Intake – enlarging the oval inlet to the factory air box - +2 HP (this modification eliminates the VFAD intake duct.).
2. Headers – approximately 4 HP peak power gain.
3. Mufflers – muffler & connecting pipe - 2-3 HP.
4. Removing the muffler from the car (engine) – about 4 HP.
5. Remove catalytic converter and resonator from the engine completely, and replacing with "cat" replacement tube – max benefit 8 HP – regardless of what muffler is used (or even no muffler).

"The muffler "off" will yield about 4 HP, with a very loud exhaust note. With it "off" the car, the noise is unbelievable! We find 2-3 HP peak RPM maximum improvement from our exhaust, or any competitive system that we have tested. So someone can see from these numbers, it is quite difficult to get a lot more HP from this engine. The max potential with a header and race exhaust would be around 10HP."

 

The part I like the best is this:

"Remove catalytic converter and resonator from the engine completely, and replacing with "cat" replacement tube – max benefit 8 HP – regardless of what muffler is used (or even no muffler)"

Thus I think you should keep the stock muffler and get the midpipe..same HP Gain...thus save your money on the HKS Catback and get something else....something that will get you real performance gains such as an Aluminum Lightweight flywheel or ECU upgrade.

 

Hmm yeah.. I was expecting more from a test pipe and exhaust, like ~20hp.. but heck, 10hp aint bad considering most of the performance mods only give marginal gains anyway.

 

Are there aftermarket headers for this car?

 

Aftermarket headers are out for this car, but I think they are all sold in Japan. RE Amenyia I think sells some..not sure how to spell that company name.

The aluminum flyhweel will give you the best acceleration gain (for an Naturally Aspirated mod), plus if you go with Forced induction it is a mod that will still be usable. Taking weight of the crank is always a safe~Reliable investment.

I would get a mid pipe for sure...and swap out your stock when you have to do your emission check.

 

There are aftermarket headers for this car, but wildly expensive for very little gain. Just go for a nice hi-flow cat (RP Performance) & whichever cat back exhaust you like. Then a nice intake (Racing Beat REVi & Ram Air Duct or upcoming AEM unit).

 

why is it that everyone just takes what RB says and just takes it as fact. i have only seen dyno's of thier products yet they say others loose Hp or don;t make anything yet they show no proof of their claims. before flaming happens (I'M NOT SAYING THAT THEY ARE LYING!!!!) I am just curious if someone has done a before after dyno with midpipe/header/ catback

 

They have been spot on with dynos of their products (i.e. honest). A few people have dynoed various parts & found their claims pretty much consistent (air intakes, cat back exhausts, etc.). I have been in and test driven a few cars with the test pipe. While much louder, & I could tell a bit of a difference I think that is consistent with about a 8-10 hp gain. If you are thinking why not 20 hp gain, I could definitely say it didn't feel like that. I did a dyno with my cat back exhaust & it gained 3 hp. Later I installed a hi-flow cat (with resonator) & it added 4.5 hp. I think there have been posters who have done the RP Performance Super cat and gotten 8 hp gain. Very nice design. Smallest cat. I have ever seen, could be very close to a midpipe in flow. A long, long time ago, there was a poster who got one of the JDM headers for over $1,000 and dynoed only like +1 hp. needless to say he was pissed. Since then, I don;t think anybody has had the cajones to drop another $1000+ on headers to give anymore data.

 

wurd thanx for the non flaming response i was in all honesty curious