135i performance upgrade?

New member. Have 2007 335i convertible, planning to (up or down?)grade to 135i convertible with 7 speed.

I don't want to go IS because I live in Michigan, where we no longer have actual roads, so I think the IS suspension would kill me.

However, I am told you can get a dealer upgrade to the additional 20HP of the IS. I assume this is mostly a chip change, but what little I can find on the web suggests that there are things one should order on the 135i to ensure best results.

If anyone knows anything about this, or has links that would be useful, please let me know.

P.S. If you need a 2007 335i Convertible, let me know.

Don't do it. That N54 motor can take SO much more. Save the coin and go for the Dinan stage 2. You will walk away from just about everyone.

I'll look that up. However, concerns include:

1. I kind of like having a warranty, so what I do better not break it;
2. I've seen people complaining about having to reflash Dinan over and over, after BMW maintenance.

But I will take a look at what Dinan has ... and still hope for some info on the BMW offering.

Thanks!

What's the stats on your 135i cab? I'm looking for a weekender to complement my daily driver (335)

I don't don't have a 135, sorry if i was unclear. I'm getting one. decided on a 135is. i had been considering a 135i so as to avoid buckboard suspension and was asking about the horsepower upgrade.

I do have a 2007 335i convertible, blue/beige, 53K miles, very sound, some paint chips and scratches, near Ann Arbor Michigan. has been my daily in good weather, housed during winter, typically december-april.

I also have a very nice '89 Porsche 911 Carrera 4, guards red, 39Kmiles, if you're really crazy.

At the moment, I have a new 135is convertible in the pipeline, plan to trade the 335i and not the Porsche.

Thanks,