Wanted to see if you guys have any thoughts about the SI/SO and SI/DO magnaflow systems. adv/disadv of them. looking to put a new exhaust on my '99 F150 4x4 5.4. I've been reading the post for awhile and think that magnaflow is the way to go I just wanted to find out more about the two types. Thanks

 

I got a 99 and just put a magnaflow si/do system on over the christmas. i gotta say it looks nice, and sounds nice. its not too loud that its straight redneck, but there is enough rumble to let you know its there. though the installation didnt go as smooth as it should have...it took a little more than just bolting on mess cause one of the pipes wasnt long enough, oh well im satisfied

 

I went si/do myself even though from what I've read here, si/so will give you slightly more hp gain. I just like dual pipes. I really like the sound too.

 

Thanks for the help. Another concern I had was the size of my spare tire. i have 17's and a lot of DO systems don't work. Anyone else have this problem. i'm going more towards SI/SO right now though.

 

I installed a SI/DO system this fall, and NO problem on my 17"s...although the spare is only a 16" (damn cheap Ford!).

 

its cool with a 17 spare, it worked on mine....should be fine

 

I talked to a tech at Magnaflow and he told me the si/do makes slightly less HP and way less torque than the si/so...but you dont actually LOSE torque like so many other si/do's on the market. I opted for the si/so...It finally arrived, its gorgeous, the polished 4 inch tip looks killer and the muffler itself is also polished stainless, great quality all around...lol, but I havent installed it on the truck yet

 

actually i felt like mine gained more torque than hp..... but troyers website says something of the sort a hp gain of 15-17ish whatever, but in all actuality, divide that in half and it is probably more realistic, i dont believe all those numbers. just to help sell the product.

 

Went with SI/SO and love it. It took me 45 minutes in my driveway to install it as well. The quality, fit, and finish is top notch. The sound isn't overpowering at all either. I tow a boat, so I didn't want to dump exhaust on it everytime I towed it. I can't say anything bad about it. Check out my gallery to see some pics of it. Good Luck!
Brian

 

I have a 01 Screw 4x4 and took off a SI/DO and put on the Magnaflow 15609 SI/SO. Noticeable improvement in sound and performance.

 

Thanks for all the help guys. I hope to make a buy in the near future!

 

Is the 4 inch tip already welded on or do you have to have it done?

 

its welded in and looks great! The whole unit bolts right up.