05stangkc

Never Had an Issue in Ca. For Different Mufflers as Far as Smog Check, But Now Big Brother Want's to Listen! I would Advise a Mellow Muffler Just In Case . In Our Area this would **** Off All the Harley Riders!

https://www.msn.com/en-us/news/us/lo...nia/ar-AAX5DpC

KC

https://leginfo.legislature.ca.gov/f...02120220SB1079

Bert

Mufflers obviously do not affect emissions in any way, so it should have no impact on sniffer test; but I'm pretty sure that technically ANY exhaust system modification is illegal in California ... they used to let it slide, but I think they might be getting more sticky about it ... good news is that it is easy to change these mufflers, so yeah hang on to the factory ones just in case!

Siber Express

That is why I have Borla Touring on mine. Nice and mellow.

m05fastbackGT

Long as the stock cats are retained, Borla S-Type and Borla ATAK are fairly just as quiet as stock, until hammering the throttle

Siber Express

I am California Drive By Compliant and CARB Legal. BBK Short tube headers, Cut and Clamp True X-Pipe and Borla Touring. Stock Cats and Resonators.

m05fastbackGT

You're most definitely good to go!

CharlieH

I have my Borla S-type installed and it sounds fantastic! On the highway cruise there is a little more noise than before but I do not mind at all. Only start to make a loud, nice sound when I put the foot down.

CharlieH

Update,

I had the gear changed and the speedometer reads accurately without me doing anything. I guess a Calibrator is not needed?

05stangkc

Ok, How are you Checking this you Certainly Have My Curiosity Peaked. Back in the Day I would get an All Stock Newer Vehicle to Set the Cruise at Say 60 Mph At That That Point They would Stick arm out the Window And Then I would Pace Other Car and See where My Speedo read! I'm sure you Must Be Using Some Sort of App to Check??? Might Try this Old School Trick Just to Be Sure. In Theory Your Speedo Should be Off 5-7 Mph, That is Just a Guess!

KC

CharlieH

I always use google map app on my phone to get around, it is not super accurate but no more than 3 mph usually. I used google map after the gear got installed and it was just like before.

05stangkc

Well, It's Up to You But an Old School Test would Confirm your Findings. 3 Mph Off would Be Acceptable on the Outside By Old School Standards. Let Us Know if you Try! Make Sure Your Pace Car is Completely Stock & Reliable. I got a Feeling It's Going to Be Off By More but Regardless you Will Have a Bit More Piece of Mind! And a bunch of Old Gear Heads Won't Be Scratching Our Noodles! Also Do You Have Taller Than Stock Rear Tires?? That would Offset Change a Bit!

Oh and How Does the Car Feel Performance Wise Etc. Overall Driving Impressions?


KC

CharlieH

Ok, if anything thing is off, I still have my speedo calibrator. So no problem there happily.
The guy who installed my gear did a good job, he tests drive it after done and found out it was too tight and he recalibrate the gear so there is no noise. I haven't floored it too much, but I notice a faster acceleration. Seems pretty good!

m05fastbackGT

Congrats and hope it all works out well..

Bert

If you change the rear gear ratio, the speedometer (and odometer) will definitely be thrown off by the same percentage as the gear change. For example, if you go from 3.31 to 3.73 rear gear ratio, that is a 12.7% change (3.73/3.31=1.127) and the speedometer will read 12.7% high versus the actual speed of the car, because the car is going 12.7% slower at the same engine RPM and transmission gear than it was before.

Rear tire diameter figures in to this the same way -- vehicle speed is proportional to the tire diameter, or "revolutions per mile" (at the same engine RPM, transmission gear ratio, and rear gear ratio)

It is possible that it was off before (don't know if there were any previous changes, and if they were corrected) and the change brought it back closer to "correct" ; or the difference is small enough that you can't measure it with the cell phone GPS.

Siber Express

They Car has a generic speedo tune for the 17 inch tires on them both the 18 and 19 inch are smaller with the 18 1.5 miles off at 60 and the performance package over 2 mph off. Tire wear and actual size differences from the manufacturer effect it also. I noticed Tach VS Speedo differences after putting my tune in.

CharlieH

Maybe the guy has corrected the speedo for me? I didn't ask...
Because when I tried my speedo calibrator yesterday to set my gear ratio as 3.73, the speedo actually went off! And then I returned the setting to the factory, the speedo is correct again.
This is a mystery for me now, if I have the chance I will ask the guy who installed the gear.

CharlieH

Update,

This is all strange... I compared my old video and found out my rpm at 80mph is the same with the stock gear and new gear! All at 2000 at 80mph.
The guy couldn't lied about the gear install... So I'm guessing maybe the part I ordered is somehow wrong? I double-checked and what I ordered is 3.73 from ford performance.
​​​​​​​This is strange...

05stangkc

I would Advise the Old School Test with Pace Car to get all your Ducks in a Row as Well! On a Side Note Gears are Normally Engraved With Tooth Count. I can't Imagine any Tech of Note Not Checking These Before Install!

Well Here you Go!

80Mph = 2600 Rpm????

You Tube

KC

CharlieH

Thanks!
I also asked the guy who installed my gear if he remembered if the new gear is actually the 3.73 gear because I did not check when the box arrived...
Yes, at 80mph, my rpms are at 2000 before the change and after... Doesn't seem normal, I will find out and update later.

Bert

Is that 80 MPH the speedometer reading, or actual correct speed per some other source, such as GPS?

If it is the speedometer reading, it didn't change because it has not been corrected. The speedometer reading is a calculated value, not the actual vehicle speed. I think it is calculated from drive shaft RPM, rear gear ratio, and rear tire outer diameter (tire revolutions per mile). The amount of speedometer error depends on which gears you had before the change, and whether the speedometer was correct before the change or not.

(driveshaft RPM is the product of engine RPM and transmission gear ratio, but I think the system actually measures the driveshaft RPM rather than calculating it from engine RPM and transmission gear ratio)

If you went from 3.31 to 3.73 gears, and the speedometer was correct before that change, and you didn't change anything else (such as rear tire outer/overall diameter) and you didn't "recalibrate" the speedometer, then the speedometer is reading high by about 12.7%; meaning when the speedometer says 80 MPH, the actual real correct speed is 80 - (12.7% x 80) = about 70 MPH