Here's the deal... Some guy offered me an amount I couldn't refuse for my Mugen Twin Loop axleback. So I jacked up the Si, started to untorque the bolts, and snap and crunch the bolts broke off. Anyway, I did this last Friday and since my new exhaust (Tananbe Super Hyper Medallion) will be here on Thursday, I figured it wasn't worth my time to get the bolts off, get new bolts, and put the stock axleback on. So since then, I've been running with no axleback. It's hella loud and annoying, but the weird thing is that I've gotten the best gas mileage I've ever had with this car. I still drve the same with occasional visits to vtec if ou know what I mean:naughty:. I'm not empty yet, but it seems like I'm on pace to get well over 300 miles on this tank.:thumbup: I never hit 300 miles per tank. Now I did just switch back to stock 15's, but I was also on 14" steelies for 2 weeks prior, so that has nothing to do with it. Just kinda weird....

 

I'm guessing it is you driving the car gentler due to noise, even if it is unconciously. :dunno:

A straight through like the twinloop isn't going to affect your engine that much.

 

less backpressure is better for gas mileage

 

plus you have to think about the fact that you have less weight due to the missing exhaust section...

 

The missing weight doesn't make up for that much in the gas economy view. What is more likely is that your stock muffler was restrictive and possibly clogging, in which case, relieving the back pressure and increasing the exhaust velocity jumped the VE of the engine, which is good for better gas mileage.

 

I never had a stock muffler on it at all. I bought it with the Twin Loop on it. I was going to put a stock one on. As for the weight issue, the Twin Loop weighed less than 20 lbs when I shipped it out, so that is negligible. As for my driving habits, they're still pretty much the same. Heck, when I went down to Madison to pick up the GSR rims, I didn't even get 300 miles per tank. It was all highway, with 14" steelies, but at 80-90 mph speeds:naughty: ... These damn Si's do rev very high at these speeds, so it doesn't help gas mileage...

 

Less restriction lets the engine run more efficiently, which means better MPG. Good luck replacing those bolts you broke... (I'm assuming you have the spring loaded bolts.) I broke one of them on my Teg and it cost me $9.23 at the Honda dealer for a new one and all I got was the bolt, no spring! I couldn't find anything that would work anywhere else. I almost had a $1 solution working that consisted of a bolt, a nut, and a washer, but I decided to go with OEM rather than spending more time half-assing it.

 

Not 100% true, but I don't think it's worth going into a whole schpeel on the theory and application.

 

every little bit helps

 

Yea, they're the stock spring loaded ones. I have plenty of springs (from 2 other exhaust swaps). But like I said, the new exhaust wll be here in 2 days so it's not worth bothering to get them out....