Apexi Catback N1 silencer backpressure/performance question!

[SHiFT]

Hey guys, I recently bought an Apexi N1 Single Catback exhaust, and yes it is a 3". I know I know, 3" is for turbo, but hopefully in the future I'll have turbo, I just wanted to put everything on only once. I know the piping is too big for a N/A car, but will the silencer help it out as far as back pressure? Obviously it'll be quieter but judging from the pictures it looks like it restricts the airflow coming out significantly. Will this help my back pressure/low end performance? Thanks all.

heres a link to what it looks like, scroll down:

http://www.racerwheel.com/engi....html

[khilgers]

I'm sure it will help cut down on the flow of the exhaust, but I don't think it will be enough to compensate for the oversized piping.

[Nathan]

No...backpressure really isnt the issue, its keeping the velocity of your exhaust gases high thats important. The reason is that if they are travelling quickly they more effectively scavenge the leftover's from the cylinder so the next time it is filled, it is with a better mix of air and fuel. You can see how old burnt exhaust hanging around in your cylinder could restrict power so obviously when it gets removed (the higher the exhaust gas velocity the more it kinda sucks it out of there) there is more power to be had. So basically...that silencer is just going to slow things down even more and reduce power. Enjoy the high rpm fun I could be wrong though, anyone else have an opinion?

[corn322]

nathan's right. just leave the silencer out, unless it's too loud for you.

[SHiFT]

damn that really sucks, thanks for the input. The turbo project definately won't happen until next summer and maybe even longer than that. The high end is better but most of the time is spent in the low range-2 to 4K rpms. Do you think its worth the time to get a N1 muffler and have a shop do a custom catback in 2.25 - 2.5 inch piping instead? I love the quality of the Apexi and it sounds real nice but now people are just convincing me that 3" is way too much for a N/A car and I should reduce the size. I do want the best performance possible even if it does only run mid to high 15s. I could just sell the Apexi, its a ***** to ship but its basically brand new. Any opinions?

[SHiFT]

one more thing. If I spend most of my time in 2-4K like I said, would it be better to get 2.25" (or somewhere around there) inch piping if 2.5" is the highest you should go on a N/A car to get the best performance at that range? How wide is the diameter of stock piping? Thanks all.

[Touring240]

get 2.5 for n/a

gain some top end. the KA has lots of low end torque already

[240SXedUp]

Just keep the 3". If you are going turbo anyway dont waste your money on another exhaust.

[Zebrahead]

I can solve your problem. Get the HKS Hiper. I had it. It was the best sounded, perfect exhaust for the KA. It's 2.5" piping, and great quality. I'd recommend it to everyone!

Nick.