Exhaust Systems....Researched

mrnickleye · 06-03-2005, 04:30 AM

A bit about me (not for my ego, but for your open mindedness and ponderance of the info I will give from time to time). I am an ASE Certified Master Auto Tech for 20 years. (No, I don't know everything, and I DO enjoy learning something every day). I manage a very successful smog repair and performance shop here in the Mojave Desert of California. (Heavy pollution control laws here!!)

For a decade I was (retired now) a repair analyst and technical training instructor on the American Space Shuttle program. When I am interested in something, I analyze the hell out of it before I do anything or spend $$$ on it.

Now, with the internet so handy, I do even MORE research to get the MOST performance from my cars. I get alot of info from other enthusiasts, and race performance magazines, too.

I have built, tuned, and raced cars, carts, and motorcycles.
I am living on a performance budget, too, like most MKIII owners.

SO.......First Supra performance mod.....Exhaust Systems....

I read on this forum recently (like 2005)that a 3" (75mm) exhaust is the way to go. My experience indicates that is only true for the turbo motor....
Wide open breathing....
Quicker spoolup of the turbo....
Higher RPMs.

But...for a naturally aspirated motor, (and NOT a track only car running high rpms all the time), you want 'some' back pressure to give you more torque at the lower RPM's. (You know, 0 to 60 MPH, daily driving).

And remember, these cars are very heavy (mine is 3600 lbs).

Much research led me to run a 2.5" (62mm) pipe from the Cat Converter all the way out.

I went with a Magnaflow straight thru muffler (packing inside). It was "too" loud for me. It is at the end of the pipe, and it created an awful drony, deep tone at cruising of 2k RPMs. I could not even listen to the stereo.

So...I ADDED a 24" long straight thru glass packed muffler, same 2.5" inside dia., and 4" diameter outside, in the middle of the system (middle of car).

Now it has a GREAT sound, with an UNRESTRICTED flow, and just enough back pressure to keep my torque high at lower RPMs.

Before this exhaust mod, the car would max out at 125mph.

After this mod, I can easily go 145mph any time I want.

06-03-2005, 04:30 AM	#1
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	A bit about me (not for my ego, but for your open mindedness and ponderance of the info I will give from time to time). I am an ASE Certified Master Auto Tech for 20 years. (No, I don't know everything, and I DO enjoy learning something every day). I manage a very successful smog repair and performance shop here in the Mojave Desert of California. (Heavy pollution control laws here!!) For a decade I was (retired now) a repair analyst and technical training instructor on the American Space Shuttle program. When I am interested in something, I analyze the hell out of it before I do anything or spend $$$ on it. Now, with the internet so handy, I do even MORE research to get the MOST performance from my cars. I get alot of info from other enthusiasts, and race performance magazines, too. I have built, tuned, and raced cars, carts, and motorcycles. I am living on a performance budget, too, like most MKIII owners. SO.......First Supra performance mod.....Exhaust Systems.... I read on this forum recently (like 2005)that a 3" (75mm) exhaust is the way to go. My experience indicates that is only true for the turbo motor.... Wide open breathing.... Quicker spoolup of the turbo.... Higher RPMs. But...for a naturally aspirated motor, (and NOT a track only car running high rpms all the time), you want 'some' back pressure to give you more torque at the lower RPM's. (You know, 0 to 60 MPH, daily driving). And remember, these cars are very heavy (mine is 3600 lbs). Much research led me to run a 2.5" (62mm) pipe from the Cat Converter all the way out. I went with a Magnaflow straight thru muffler (packing inside). It was "too" loud for me. It is at the end of the pipe, and it created an awful drony, deep tone at cruising of 2k RPMs. I could not even listen to the stereo. So...I ADDED a 24" long straight thru glass packed muffler, same 2.5" inside dia., and 4" diameter outside, in the middle of the system (middle of car). Now it has a GREAT sound, with an UNRESTRICTED flow, and just enough back pressure to keep my torque high at lower RPMs. Before this exhaust mod, the car would max out at 125mph. After this mod, I can easily go 145mph any time I want. __________________ Had a Red 1989 N/A. Automatic. Sports Pkg. w/wing. TEMS, and some nice MODS. Sold to a friend 10/08/08. Last edited by mrnickleye; 02-27-2007 at 05:17 AM.