This has been very exhausting experimentng for a solution for my MYVI 1,3 Auto tranny Exhaust Solution.
I have purchased from a friend HotBits 4 to 1 Extractor which was fitted nicely to replace the stock extractor.

At Beginning the Extractor mod alone has brought in large difference in pickup for my Auto Myvio but still the power seem to be blocked and rpm is high before
actual power is felt and delivered..

I contacted Kweng for his recomendation according to my Budget..

I informed hin that my Issue was low to mid power restriction/loss due to the stock bullet and s-mufler.
He initially recommended that i only change the S-Mufler . I head myself to GT Racing Workshop in puchong to try to solve my issue.

After Meeting his mechanic in Puchong .. the Mech spent a lengthy time to explain his experienced on modding a Myvi 1.3Auto.
According to this Mechanic I need to change my hole front piping from the stock 1.6" to 2" and rathwer then changing the stock S-Mufler only change the Bullet.
They developed a Bullet Design to solve the "kick Back Effect " which was originally delivered by the CatCon.

This Cat Con apparently according to the mechanic not only is used to absorb harmful gas but also utilise by the car to push the low-mid range rpm that was needed
that was lost during Auto Transmission.

The Solution was to take a 12" Straight Flow Bullet and put in a slighly smaller pipe maybe 2-3" in length and fit it into the inner diameter of the Bullet. This smaller full pipe will block some of the perforated holes that exist inner side of the bullet. This somehow will create a "Kick Back" effect similar like the Cat Con.

The second stage was to replace the 1.6" stock pipe right from the joint of the Extractor to the Bullet itself. This will be end to end 2" pipe.
I was trully confident and the skill that the mechanic has. He seems to know what his doing since he mentioned he has done this method for lots of auto Myvi.

The Job was done. Now time for testing...[I]

I noticed the following..

After Changing the pipe from 1.6" to 2" the sluggish effect still exist and now the power band which exist before the mod has now decreased. Before the powerband starts from 2K up to 6K . Powerband now onlly starts actual at 3K to 6K. This somewhat produce the Screaming effect. Which is audible from the 12" bullet Mod. I really have to push the peadl to ensure that power is delivered. The power is not as effecient as before..

I have tried to contact Kweng on this issue it seems he is busy even to answer my SMS. I want to make it clear that.. if the Issue was the upgrade to 2" piping please confirm it here. As the workshop insist that the piping be changed. Since the mod i have extensively read Lowyat and Zeroto100 forum and most thread mentioned for Auto Tranny it is not adviseable to change to a bigger diameter piping. This will in turn increaseFc and makes the car feels like it is struggling to be pushed.


I am confused regarding the conflicting solution that the Mechanic and Kweng offered. I think my issue can be solved by fitting back the old 1.6" piping to the new bullet or better to change to the new 1.6" piping if the cost is not reimbursable.. but i need a solutin asap.

I know Kweng has good reputation in Lowyat interms of exhaust . I hope Kweng you can answer this issue asap.

JOe

This post has been edited by mizzdelina: May 6 2011, 06:45 AM

Thanks bro. i be patient n wait.. Since the exhaust mod I have reset the ECU as you suggested earlier.

Findings:

Car runs superbly Optimum performance during the day (HOT Day) but opposite Night. Also FC has increase tremendously since the Exhaust MODS.. Im avergaing about Rm65 @ max 270KM/L ..so thats 4Km per 1 Litre of RON 95 ( FAST HANTU DRIVING)

Let me know what could be the issue..

Is it imperitive we change the S-Muffler ? Top Speed now stagnant at 160Km/h. The ECU is learning fast too compensate for the change in powerband that the piping has caused..but sadly this is done at a cost of more Fuel. I really think changing back the piping to 1.6" is the key.. I dont think the bullet mod help much.. maybe a swirl Bullet and an s-muffler with dual pipe output could do the trick here.

Maybe you could refer to the customer Auto Database for eg on solutions. As mentioned i prefer low and mid power with compensation of top speed..i think at current 160KM/h its reasonable .. just need to tweak the setup as to not each so much FC..

Also i saw my rpm drop after the exhaust mod..maybe round +/- 200rpm

FYI my MODS

APM Performax Springs
600C Racing Brake Pads
Alloy Lightened Pulley
16" Advanti Racing Alloy RIMS + Archilles 205/45/16
Pivot MegaRaizin Purple
HKS Electric King Earth
HKS grouding Cables
Bosch Iridium Plugs
Blitz Drop In Air Filter