Hey guys, I was looking into getting a header and exhaust for my '04 R53. But I just want to make sure there aren't any other greater horsepower adding mods I should do first? I currently have an DDMWorks Intake and an Alta 17% reduction pulley.

 

As stated by a member's sig: "If you can't go fast with 90 hp, 900 won't help you."...unless HP bragging rights is all you're looking for.
The very best money you can spend on the R53 is for handling. A 22 MM adjustable rear sway bar and responsive struts like the KONI FSD are the best bang for the buck you can get. The MINI will only go so fast because of it's wind profile and to go a lot faster requires a geometric jump in HP that just can't be accomplished with the existing engine.

 

^This^

Some low-hanging performance Fruit for the R53:

-Pulley/Belt
-Rear Swaybar
-Good Tires
-Polyurethane control arm bushings.
-Custom engine tune

 

I would skip the header. I like changing the Cat-Back exhaust more for sound than performance (but there is a little HP gain).
I also agree with making suspension upgrades over engine mods. Springs, Shocks, Rear Sway Bar, Front Camber Plates, and Tires (plus lighter wheels if within budget).

 

Check out our Stratmosphere exh or the Milltek, both give nice torque gains without drone. Then skip the header as they are expensive for little gains. We have had really good results with our WMW Mild Street cam as it's cost effective and noticeable gains.

 

Alright, I planned on going with some Meagan Racing Euro street coils, Hotchkis rear control arms, and Eibach front and rear sway bars. Is this a good setup for spirited street driving and maybe an occasional track day?

 

I have been looking at your cam for some time and will certainly be getting it after I get my suspension mods sorted out.

 

The ST coil overs are the best bang for your buck coil, in my opinion. They're even manufactured by KW so you know they're quality. I've installed these on everything from daily drivers to big HP builds and they handle very well. They also last and I have not seen any issues with them. If you want an economically priced coil over, that is the coil I'd suggest going with. Those matched with Powerflex bushings, the Hotchkis Adjustable Control Arms, and a rear sway bar, your MINI will handle quite well on the street and the track.